Conjugated Microporous Polymers with Dimensionality-Controlled Heterostructures for Green Energy...

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Conjugated Microporous Polymers with Dimensionality-Controlled Heterostructures for Green Energy Devices

Xiaodong Zhuang , Dominik Gehrig , Nina Forler , Haiwei Liang , Manfred Wagner , Michael Ryan Hansen , Frédéric Laquai , Fan Zhang , * and Xinliang Feng *

Dr. X. Zhuang, Prof. F. Zhang, Prof. X. Feng School of Chemistry and Chemical Engineering Shanghai Jiao Tong University 200240 Shanghai , P. R. China E-mail: [email protected]; [email protected] D. Gehrig, Dr. N. Forler, Dr. H. Liang, Dr. M. Wagner, Dr. M. R. Hansen, Dr. F. Laquai Max-Planck-Institute for Polymer Research Ackermannweg 10 , 55128 Mainz , Germany Dr. M. R. Hansen Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry Aarhus University Gustav Wieds Vej 14 , DK-8000 Aarhus C , Denmark Prof. X. Feng Center for Advancing Electronics Dresden (cfaed) and Department of Chemistry and Food Chemistry Technische Universität Dresden Mommsenstrasse 4 , 01062 Dresden , Germany

DOI: 10.1002/adma.201501786

a π-conjugated fashion and possess continuous networks. Such structural features are unique and usually not available in other porous materials. CMPs have attracted signifi cant research interests in optoelectronics because numerous photo-electrical building blocks can easily be made available. Most of the reported works have focused on p-type building blocks, such as carbazole and tetrakisphenylethene, and corresponding CMPs’ photoluminescence properties. [ 17–19 ] The introduction of electron-accepting (n-type) species will result in charge/energy transfer between p/n components, which will greatly expand the application of CMPs, such as for light-emitting and photo-voltaic devices and nonlinear optics. To realize this, one effi cient way is to physically fi ll or chemically bind an n-type molecule, such as fullerene, into p-type-conjugated polymer networks. The resulting covalent/conjugated organic frameworks-based on donor–acceptor heterostructures have shown very prom-ising application for charge separation and photo energy conver-sion. [ 20,21 ] However, the acceptor molecules in these systems are all present in pore channels, resulting in a signifi cant decrease in the specifi c surface area.

In this study, we demonstrate a series of unprecedented p/n heterostructures comprising CMPs (acting as donors, and thus denoted as D) and nanocarbons (acting as acceptors, and denoted as A) with controlled dimensionalities of 0D, 1D, or 2D, employing bromo-functionalized carbon nanospheres (0D CSs), single-walled carbon nanotubes (1D SWNTs), and reduced graphene oxide (2D RGO) as structurally directing templates. Halogenated BODIPY (M1: 2,6-diiodo-1,3,5,7-tetramethyl-8-phenyl-4,4-difl uoroboradiazaindacene) was chosen as the key monomer for polymerization with 1,3,5-triethynylbenzene (M2) through the metal-catalyzed Sonogashira–Hagihara coupling reactions on the template surface. The resulting CMPs had well-defi ned nanosphere, nanotube, and nanosheet morpholo-gies, inheriting the original architectures of the nanocarbons. The specifi c surface areas of these dimensionality controlled CMPs (593–622 m 2 g −1 ) were higher than the CMP (574 m 2 g −1 ) obtained without use of a template. The H 2 isosteric heats for these CMPs ( Q st = 7.7 ± 0.2 kJ mol −1 ) at zero coverage were unaffected by the nanocarbon templates. Importantly, an effective inverse decay rate ( τ eff ) reduction of 38–46% for nanocarbon-directed CMPs in comparison with that of amor-phous CMP was observed, indicating a strong electronic inter-action between the nanocarbons and the polymer networks, with the most pronounced interaction observed for CMP-2D, followed by CMP-1D, then CMP-0D (CMP-2D > CMP-1D > CMP-0D). Further, the CMP- n D were readily converted into boron/nitrogen (B/N) co-doped porous carbons with main-tained 0D/1D/2D morphologies by direct pyrolysis. The porous

Porous polymers, [ 1 ] a type of polymeric material containing numerous pores, possess high specifi c surface areas and tailor-able chemical compositions, and are easily available through many classical polymerization methods and from many organic monomers. Covalent organic networks, [ 2 ] polymer aromatic frameworks, [ 3 ] polymers with intrinsic microporosity, [ 4 ] covalent organic frameworks, [ 5 ] and conjugated microporous polymers (CMPs) [ 6 ] and ionic polymer networks [ 7,8 ] are typical porous polymeric materials featuring high porosity, light weight, and structural variations. However, due to the lack of proper syn-thetic protocols, most of the reported porous polymers present nanosphere or monolith architectures due to their rapid precip-itation from reaction solvents. Mini-emulsion polymerization [ 9 ] and silica-based hard-template methods [ 10 ] have been used for the construction of microporous polymer networks with quasi-0D structures. However, these protocols produced the desired morphology for porous polymers at the price of a signifi cantly decreased specifi c surface area. [ 11 ] Porous polymers with a large specifi c surface area and a high carbon yield [ 12 ] can serve as pre-cursors for preparing heteroatom-doped porous carbons, which hold great promise as metal-free catalysts for the oxygen reduc-tion reaction (ORR), [ 13 ] and as advanced electrodes for super-capacitors [ 13 ] and other clean-energy devices. [ 14 ] Clearly, the morphologies and microstructures of porous polymers and the resultant porous carbons exert signifi cant impact on the perfor-mance of energy devices. [ 15 ]

Among porous polymers, CMPs are a class of amorphous materials [ 16 ] that permit the linking of building blocks in

Adv. Mater. 2015, DOI: 10.1002/adma.201501786

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573 m 2 g −1 ), and high B/N doping contents (N = 5.1–8.6 wt%, B = 0.6–0.9 wt%), leading to an effi cient catalytic performance (half-wave-potential = 0.71 V vs the reversible hydrogen elec-trode (RHE), diffusion limiting current density ≈6.0 mA cm −2 , four-electron transfer mechanism) for the ORR. The reliable structure–property relationship 2D > 1D > 0D was established between the electrochemically catalyzed ORR and the nano-structures. As an air electrode, these nanocarbon-based zinc–air batteries manifested strong relationship between morphology and performance (2D > 1D > 0D), and the current density and peak power density for 2D porous carbon reached 23.9 and 14.6 mW cm −2 at 0.61 V, respectively. Thereby, these unique structural features of porous polymers with controlled dimen-sions provide a new insight into porous materials for multiple functions.

The strategy for the synthesis of CMPs with different dimensionalities is presented in Figure 1 , using CSs, SWNTs, and RGO as the 0D, 1D, and 2D templates, respectively. The preparation of CSs (≈7 nm) is demonstrated in Scheme S1

(Supporting Information). First, the nanocarbon templates were functionalized by treatment with a p-bromobenzene diazonium salt in water. The obtained bromo-functionalized carbon templates (CS-Br, SWNT-Br, and RGBr) were highly dispersible in various organic solvents, such as dimethylform-amide (DMF) (≈1.0 mg mL −1 for all samples). Next, halogenated BODIPY (M1) was mixed with 1,3,5-triethynylbenzene (M2) and the functionalized nanocarbon in anhydrous DMF along with catalytic amounts of [Pd(PPh 3 ) 4 ] and CuI. The reaction mixture was sealed and stirred under Sonogashira–Hagihara reaction conditions. After 72 h, the precipitated black solids were collected and purifi ed by Soxhlet extraction. Finally, 0D ball-like, 1D stick-like, and 2D sandwich-like CMPs, denoted as CMP-0D, CMP-1D, and CMP-2D for the CS-, SWNT-, and RGO-containing polymers, respectively, were obtained in high yields (≈90 wt%) after vacuum drying. For comparison, amor-phous-type CMP (CMP-Amor) was also prepared by the same procedure without the use of a nanocarbon template.

As polymerization on the template surfaces proceeds, polymer networks generally precipitate from the solvent;



Figure 1. Dimensionally controlled synthesis of BODIPY-based CMPs and the corresponding B/N co-doped porous carbons employing nanocar-bons as templates. i) Argon, Pd(PPh 3 ) 4 , CuI, Et 3 N, DMF, 80 °C, 3 d; ii) 4-bromobenzenediazonium tetrafl uoroborate, 0 °C to room temperature, 2 h; iii) argon, M1, M2, Pd(PPh 3 ) 4 , CuI, Et 3 N, DMF, 80 °C, 3 d; iv) argon, pyrolyzed at X °C (X = 700, 800, and 900) for 2 h. BN, boron, and nitrogen co-doped porous carbon.

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therefore, the degree of polymerization and the presence of terminal groups may affect the porosity of the resulting mate-rials. Initially, solid-state 13 C{ 1 H} cross-polarization/magic-angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy was employed to analyze the molecular struc-ture and the infl uence of the carbon template on the resulting CMPs ( Figure 2 ). For the pure monomer M1 (Figure 2 e), the spectrum includes narrow and sharp 13 C signals, suggesting a crystalline structure with well-defi ned geometries. [ 22 ] Remark-ably, the spectrum only includes about half the number of 13 C resonances expected from M1 (see the inset in Figure 2 d and Figures S1, S2, Supporting Information). [ 23 ] This is attrib-uted to one distinct molecular conformation of the phenylene moiety, leading to a highly symmetric, extended aromatic system. [ 24 ] The reaction of M1 with M2 leads to a clear high-fi eld shift of ≈4–7 ppm for the methyl groups at positions 14 and 15 (cf. Figure 2 a–d). Moreover, cross-linking with the nanocarbons resulted in a signal decrease accompanied by an increase in the 13 C line width. This is a consequence of the tightly cross-linked CMP materials, where free radicals from the nanocarbons induce signal loss and line broadening for the 13 C nuclei of the polymer network (more effective T2 relaxation mechanism). [ 25 ] However, all CMP- n D materials (Figure 2 a–d) show similar structural information in comparison with that of CMP-Amor (Figure 2 e), indicating that the incorporation of

nanocarbon templates did not affect the polymerization reac-tion signifi cantly.

By comparing the Fourier transform infrared (FTIR) spectra of CMP-Amor and CMP- n D ( n = 0, 1, 2), a peak with a very low intensity at 2110 cm −1 that corresponds to the alkyne

C C stretch was observed. The intense alkynyl C H stretching near 3300 cm −1 almost disappeared in the spectra (Figure S3, Supporting Information). These results are sugges-tive of a high degree of polymerization in the carbon template-mediated synthesis of CMPs. The chemical nature of the CMPs was further investigated by X-ray photoelectron spectroscopy (XPS). All four CMPs showed almost the same heteroatom com-ponents. Typically, the N1s, B1s, and F1s spectra of CMP-2D are presented in Figure S4 (Supporting Information). The peaks at the binding energies of 399.5, 191.6, and 685.6 eV can each be fi tted by only one component, which can easily be attributed to the N and B species of the N B bond and the F species of the B

F bond, respectively (atomic ratio for N/B/F: 2.00/0.43/2.07). The morphologies of the as-prepared CMPs were inspected

by scanning electron microscopy (SEM) and transmission elec-tron microscopy (TEM). As shown in Figure 2 f–k, many free-standing ball/stick/sheet-like nanomaterials with morphologies similar to those of nanocarbon templates can be recognized. Based on the same ratio of nanocarbons (65 mg) to monomers (M1, 800 mg, 1.5 mmol; M2, 200 mg, 1.5 mmol), the obtained



Figure 2. Structural and morphology characterization of CMP-nD. a–d) Solid-state 13 C{ 1 H} CP/MAS NMR spectra of: CMP-2D (a), CMP-1D (b), CMP-0D (c), CMP-Amor (d), and M1 (e), recorded using 25.0 kHz MAS and high-power 1 H and 19 F decoupling during acquisition. Assignments follow the chemical structures shown in (a) and (e). f–k) SEM (left) and TEM (right) images of: CMP-0D (f,i), CMP-1D (g,j), and CMP-2D (h,k).


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20 ± 4 nm (Figure 2 f,i); in contrast, CMP-1D had a diameter and length of 150 ± 30 nm and 0.6–2 µm, respectively (Figure 2 g,j); and the nanosheet (CMP-2D) had a lateral size of between 1 × 1 and 4 × 4 µm 2 and a thickness of about 80 ± 10 nm. No free porous polymer particles or naked carbon templates can be observed in either the TEM or SEM visualiza-tions, suggesting that most of the monomers have been polymerized on the nanocarbon surface. The control sample CMP-Amor pre-pared without use of a template exhibited the amorphous nanoparticle (≈10–20 nm) structure (Figure S5, Supporting Informa-tion). Notably, the thickness of the porous polymer shells on nanocarbons could easily be adjusted by controlling the template/monomer ratio. As shown in Figure S6 (Sup-porting Information), CMP-1D with three different diameters, 35 ± 5, 100 ± 15, and 210 ± 20 nm, were obtained by adjusting the template/monomer ratio of 65 mg/0.5 mmol, 65 mg/1.0 mmol, and 65 mg/1.5 mmol, respectively. Consequently, these results highlight the crucial role of the carbon template as a substrate for directing the morphology of the resultant CMP in a 0D, 1D, and 2D manner.

The porous nature of CMP- n D ( n = 0, 1, 2) was confi rmed by nitrogen physisorption measurements. It was found that the isotherms of all the CMP- n D variants and CMP-Amor are type I (Figures S7–10, Supporting Information). The Brunauer–Emmet–Teller (BET) surface areas ( S BET ) of these polymer net-works varied between 574 and 622 m 2 g −1 (Table S1, Supporting Information) and had a similar pore diameter of 1.6 nm, which is a typical microporous (<2.0 nm) character. Typically, the spe-cifi c surface area of CMP-Amor was 574 m 2 g −1 , which is com-parable to those reported for CMPs (200–900 m 2 g −1 ) based on aromatic building blocks. In contrast, CMP-0D, CMP-1D, and CMP-2D yielded BET surface areas of 622, 614, and 593 m 2 g −1 , respectively. The pore size distributions of CMP-Amor and CMP- n D are presented in Figures S7–10 (Supporting Informa-tion). Unlike reported procedures, [ 9,11 ] these results indicate that employing 0D, 1D, and 2D nanostructured carbon tem-plates in the preparation will not affect the pore structure of CMPs.

We further investigated the exciton dynamics of CMP-Amor and CMP-nD by time-resolved photoluminescence spectros-copy. The emission spectra obtained by multivariate curve resolution alternating least-squares (MCR-ALS) analysis of the emission data (see Figure S11, Supporting Information) are presented in Figure 3 a. Two components are necessary to accurately describe the data. From Gaussian fi ts to the spec-tral data, the emission peaks at 1.782/1.800/1.828/1.851 eV (696/689/678/670 nm) shift to 1.626/1.657/1.692/1.716 eV (763/748/733/722 nm) for CMP-Amor/CMP-0D/CMP-1D/CMP-2D after excitation, respectively. These shifts might be induced by a change in the dielectric constant in the sur-rounding medium of the chromophores. Furthermore, the

dynamics of components 1 and 2 of CMP- n D and CMP-Amor were described with a biexponential decay function. The emis-sion of component 1 is attributed to a monomer-like emission, which is in agreement with the previously published diethynyl-BODIPY dyes with additional electron-donating groups exhib-iting emission maxima up to 659 nm. [ 26 ] Moreover, the emis-sion of component 2, which appears strongly redshifted with respect to component 1, is consequently assigned to polymeric states distributed over a higher number of chromophores.

The corresponding concentration profi les of components 1 and 2 are depicted in Figure 3 b. Analysis of the time-dependent concentration profi les of the two components shows that the emission at high energy is shorter lived compared with the emission at lower energy. In fact, component 2 shows an ini-tial rise from 32 to 45 ps, which seems to be correlated with the decay of component 1. A magnifi cation of the relevant data is presented in Figure S12 (Supporting Information). Further-more, components 1 and 2 of each compound were described with a biexponential decay function. The fi tting results are summarized in Table S3 (Supporting Information). The fi t-ting yields an effective inverse decay rate τ eff that is reduced by 38.5%, 40.0%, and 46.1% if carbon-rich materials such as CS (CMP-0D), SWNT (CMP-1D), and graphene (CMP-2D), respectively, are attached to the polymer network (CMP-Amor). It appears that this is a straightforward consequence of the cou-pling of the p-type polymer network to the n-type nanocarbons, indicating electronic interactions in the p/n heterostructures. It is noteworthy that the reduction in the τ eff of component 2 is most effi cient in the case of CMP-2D, indicating that the inter-action between the polymer network and graphene is more pro-nounced than that with CS or SWNT. On the one hand, this might be a consequence of better geometry matching between CMP-Amor and graphene than with SWNT or CS. On the other



Figure 3. Time-resolved photoluminescence. a) Emission spectra and b) concentration profi les of component 1 (fi lled symbols) and component 2 (open symbols) from MCR-ALS analysis of emission data.


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hand, long-distance transport in graphene (which exceeds the transport in SWNT and CS) is another factor determining elec-tronic communication in CMPs. In line with this argument is the steady redshift of the emission maximum for the series CMP-0D, CMP-1D, and CMP-2D with the strongest redshift for CMP-2D. This result (0D < 1D < 2D) is most likely due to a gradually increasing charge-transporting distance and electron-accepting properties for CS, SWNT, and graphene.

Various clean energy devices, such as Li-ion batteries, supercapacitors, and fuel cells, have been developed for port-able electronics and vehicle electrifi cation. However, devel-oping novel devices with higher energy/power densities, such as metal–air batteries, [ 27–29 ] Li–sulfur batteries, [ 30,31 ] etc. [ 32,33 ] is a major challenge. From a materials perspective, carbon is low cost, precursor selectable, component controllable, and nanostructure processable; therefore, varieties of carbon-based nanomaterials have been developed for application in these new energy devices, including hollow carbon spheres, carbon nanotubes, and graphene-based sheet-like or sponge-like car-bons. [ 34 ] Dimension-controlled porous carbon materials may provide new insights into the mechanism of these applica-tions, and help in the development of high-throughput energy devices. Given that CMPs are carbon-rich precursors, the as-prepared CMPs (CMP-Amor and CMP- n D) were pyrolyzed at X °C ( X = 700, 800, 900, 1000) for 2 h under an argon atmos-phere, affording boron and nitrogen co-doped porous carbons (denoted AmorBN-X and n DBN-X, n = 0, 1, 2, respectively, see Figure 1 ).

The chemical nature of AmorBN-X and nDBN-X was investi-gated by XPS. Owing to the similar results for these four porous carbons, only 2DBN-700/800/900 are illustrated here (Figure S4, Supporting Information). For 2DBN-X, the major contribu-tions at binding energies of around 398.4 and 400.8 eV can be attributed to the nitrogen species of the C B N and C N C bonds [ 35–37 ] (which should be pyrrolic N), respectively. The B1s spectra can be deconvoluted into two different peaks at binding energies of 190.5 and 191.4 eV, corresponding to the B species in B N and B C N bonds, respectively. Another minor con-tribution at the higher binding energy of around 184.0 eV can be assigned to the double-nitrogen-bonded boron (N B N) moieties in which the nitrogen originates from the BODIPY blocks. This strategy thus provides a feasible way to build up 0D-, 1D-, and 2D-porous carbons with a high level of boron and nitrogen doping content (Figure S4, Supporting Information: B = 0.6–0.9 wt%, N = 5.1–8.6 wt%).

B/N co-doped carbon materials [ 35–37 ] have demonstrated promising electrocatalytic performance and showed advantages over other single-heteroatom-doped carbon materials due to the synergistic effects from boron and nitrogen. The electrocatalytic activities of the B/N co-doped porous carbons prepared in this study in the ORR under alkaline conditions (0.1 M KOH) were examined. The ORR catalytic activity of 2DBN- X ( X = 700, 800, 900, 1000) was fi rst evaluated by cyclic voltammetry (CV, Figure S13, Supporting Information). It was found that the ORR peak potential of 0.69 V versus RHE for 2DBN-800 was slightly higher than the results for the other three porous carbons. Koutecky–Levich plots (K–L plots, Figure S14e,f, Supporting Information) with a good linear relationship for the 2DBN- X electrodes were calculated from linear sweep voltammetry

(LSV) curves (Figure S14a–d, Supporting Information) at var-ious rotation rates. Based on the LSV curves under 1600 rpm for 2DBN-X, 2DBN-800 showed the lowest half-wave-potential (HWP = 0.81 V) and highest diffusion-limited current density ( J DL ≈ –6.0 mA cm −2 ), suggesting a lower operation voltage and lower energy consumption ( Figure 4 a). The same temperature-dependent phenomena were observed for 0DBN- X , 1DBN- X , and AmorBN- X . Therefore, the LSV curves for n DBN-800 ( n = 0, 1, 2) were further compared with those for AmorBN-800 and a commercially available Pt/C catalyst in Figure 4 b. J DL (5.95 > 4.94 > 3.98 mA cm −2 ) and the electron transfer number (3.85 > 3.69 > 3.03) for 2DBN-800, 1DBN-800, and 0DBN-800 exhibit the strong relationship between dimensionality and electro-chemical catalyzed ORR performance. The improved catalytic performance for 2D porous carbons is believed to originate from the large lateral and layer-to-layer conductive feature (several micrometers) in comparison with the dot-to-dot and line-to-line conductive pathway of 0D and 1D porous carbons, respectively ( Figure 5 ). This result is also consistent with the above time-resolved photoluminescence studies of the dimen-sionality controlled CMP precursors. Although the HWP for 2DBN-800 is ≈39 mV lower than for Pt/C, the mainly four-elec-tron-transfer pathway ( n ≈ 3.85 at 0.5 V, see Figure 4 c) calcu-lated from the rotating ring–disk electrode (RRDE, Figure S15, Supporting Information) curve and Equation S3 (Supporting Information), together with the ultrahigh J DL , makes 2DBN-800 promising as an electrocatalyst for the ORR. The mean number of transferred electrons per O 2 molecule involved in the ORR, which can be determined from the K–L relation (Equation S1, Supporting Information), was approximately 4.0 between 0 and 0.5 V. These results highlight that the ORR proceeds via a pri-mary four-electron pathway.

In addition to their excellent ORR performance, n DBN-800 and AmorBN-800 were further employed as the air cathode in Zn–air batteries. To construct primary Zn–air batteries, the ORR electrocatalysts discussed above were loaded onto carbon-fi ber paper as the air cathode, and paired with a Zn foil in 6 M KOH. The battery had an open-circuit voltage of ≈1.40 V. At a voltage of 0.8 V, AmorBN-800, 0DBN-800, 1DBN-800, and 2DBN-800 showed current densities of approximately 7, 5, 15, and 17 mA cm −2 , respectively. The peak power densities for AmorBN-800, 0DBN-800, 1DBN-800, and 2DBN-800 at 9.7, 6.7, 21.2, and 23.9 mA cm −2 reached 6.9, 4.8, 13.2, and 14.6 mW cm −2 , respectively (2D > 1D > 0D, Figure 4 d). The cur-rent densities at 0.8 V and peak power densities for the 1D and 2D (but not 0D) porous carbons were signifi cantly higher than the porous carbon prepared without use of a template. This result indicates that 1D and 2D porous carbons capable of long-distance charge transport contribute more to oxygen reduction on an air-diffusion layer than porous carbons with confi ned 0D morphologies. Thus, this dimensionality-related catalytic per-formance offers a new platform for developing metal-free air cathodes for Zn–air batteries.

The as-prepared porous carbons were next investigated as air catalysts for rechargeable Zn–air batteries. First, these materials were mixed and loaded onto a single cathode for charge and discharge cycling experiments (Figure 4 e and Figure S16, Sup-porting Information). The electrolyte was 6 M KOH with 0.2 M zinc acetate (dissolved in KOH to form zincate, Zn(OH) 4 2− ) to




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ensure reversible Zn-involved electrochemical redox reactions at the anode. [ 29,38 ] Such batteries exhibit cycling stability when charged and discharged galvanostatically at low current densi-ties (5–20 mA cm −2 ) and short cycle times (300 s per charge or discharge period). As an example, the charge–discharge curve for 2DBN-800 is presented in Figure 4 f. Importantly, when repeatedly charged or discharged at 20 mA cm −2 for a total of 11 h with a 5 min cycling period, the battery showed outstanding cycling stability, superior to rechargeable batteries using a com-mercial Pt/C cathode (Figure S17, Supporting Information). As charging–discharging continued, the Zn foil was gradually thinned, and the electrolyte accumulated more and more soluble Zn salts (in the right-hand chamber of the device in Figure 4 g; see also the SEM image in Figure S16, Supporting Information).

The battery eventually ceased functioning when all the Zn metal was consumed. The as-prepared metal-free ORR catalyst is ideally suited for Zn–air batteries by replacing the electrolyte and offering fresh Zn, owing to its exceptional ORR activity and durability. [ 39 ]

In summary, a novel nanocarbon (carbon nanosphere, carbon nanotube, and graphene)-inspired strategy for the syn-thesis of 0D, 1D, and 2D CMPs and B/N co-doped porous car-bons with high specifi c surface areas has been demonstrated. Dimensionality has been shown to have a signifi cant infl u-ence on CMPs in respect of photoluminescence. An effective inverse decay rate ( τ eff ) reduction of 38–46% for nanocarbon-directed CMPs in comparison with that of amorphous CMP was observed, indicating electronic interactions between n-type

nanocarbons and p-type polymer networks. The porous carbons obtained herein exhib-ited high B/N doping contents and effi cient catalytic performance for the ORR, supe-rior to state-of-the-art noble-metal catalysts. Remarkably, a reliable structure–property relationship (2D > 1D > 0D) was established between the electrochemical catalyzed ORR and the dimensionality. It is expected that the synthetic strategy as well as the structure–property relationship in this work will offer opportunities for the templated synthesis



Figure 5. Conductive architectures for nanocarbon-directed 0D, 1D, and 2D porous carbons.

Figure 4. The ORR and Zn–air battery performance of the catalysts. a) LSV curves of 2DBN- X ( X = 700, 800, 900, 1000) in O 2 -saturated 0.1 M KOH solution at 1600 rpm at a scan rate of 5 mV s −1 . b) LSV curves of AmorBN-800, 0DBN-800, 1DBN-800, 2DBN-800, and Pt/C in O 2 -saturated 0.1 M KOH solution at 1600 rpm at a scan rate of 5 mV s −1 . c) Electron-transfer number for AmorBN-800, 0DBN-800, 1DBN-800, and 2DBN-800 as a function of the electrode potential. d) Polarization curve ( V – i ) and the corresponding power density plot of the battery using AmorBN-800, 0DBN-800, 1DBN-800, and 2DBN-800 as the cathode catalysts. e) The primary Zn–air battery. f) Discharge and charge cycling of 2DBN-800. g) A real Zn–air device after 48 h charge and discharge cycles. h) An LED (3.4 V rated voltage) powered by two Zn–air devices using 2DBN-800.


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of porous polymers and heteroatom-enriched porous carbons with controlled morphologies and functions that will provide an important platform for developing a variety of functional devices, such as batteries, fuel cells, electronics, and sensors.

Supporting Information Supporting Information is available from the Wiley Online Library or from the author.

Acknowledgements X.Z. and D.G. contributed equally to this work. The authors thank the fi nancial support from 973 Programs of China (2013CBA01602, 2012CB933400), Natural Science Foundation of China (51403126), and ERC Grant on 2DMATER and EU Graphene Flagship. M.R.H. acknowledges fi nancial support from the Villum Foundation under the Young Investigator Programme (VKR023122). F.L. thanks the Max Planck Society for funding the Max Planck Research Group of Organic Optoelectronics and the Deutsche Forschungsgemeinschaft (DFG) for funding in the framework of the priority program SPP1355 “Elementary Processes in Organic Photovoltaics.” D.G. acknowledges a Kekulé scholarship of the Fonds der Chemischen Industrie (FCI).

Received: April 15, 2015 Revised: April 29, 2015

Published online:

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