莆田学院易明杰/黄建辉&哈工大（深圳）张嘉恒ACB: 协同调控ZnIn2S4配位环境负载高浓度单原子Sb并应用于柔性锌空气电池

【导读】

近年来，电催化剂在反应过程中多电子转移导致的动力学迟缓和可逆性差已成为严重阻碍Zn-Air电池能量效率提高的核心科学问题。目前，杂原子掺杂，空位工程和单原子催化剂三种优化方法能够使电催化剂基底表面的局部电荷重新分布，调控电催化剂的d带中心，促进电催化性能。但单一的优化方式难以全面改善Zn-Air 电池中动力学迟缓和可逆性差的问题，而多种优化方式相结合制备电催化剂的合成步骤繁琐，因此还有很大进步空间。

【成果掠影】

近日，莆田学院的易明杰教授、黄建辉教授以及哈尔滨工业大学（深圳）的张嘉恒教授利用离子液体在ZnIn₂S₄/PC中掺入同时掺入了N/F原子、硫空位和Sb金属单原子。由于高负载的金属单原子Sb有着优异的催化性能和原子利用率，使得Sb_SANF-ZnIn₂S_4-x/PC在OER/ORR/ZAB中均有着优异的性能。DFT计算显示，金属单原子Sb，N/F原子和硫空位的协同效应可以调节ZnIn₂S₄/PC的电子结构并降低中间产物在OER/ORR过程中的能垒，对提高催化性能是有益的。因此，这种设计提供了一种简单的策略在基底中同时掺入了N/F原子，硫空位和高负载量的Sb单原子，为进一步提高OER/ORR的催化效率提供了新的思路。

该成果以莆田学院为第一单位以题目“Ionic liquid meets ZnIn₂S₄: Synergistically tuning coordination environment of ZnIn₂S₄ grown on porous carbon by N, F doping and S-vacancies to load high concentration of single-atom Sb for efficient flexible Zn-Air batteries”发表在中科院一区期刊Applied Catalysis B: Environment and Energy上。

【核心创新点】

该工作使用离子液体将S空位，N/F原子和单原子Sb在层状ZnIn₂S₄基底上一次性产生,并均匀负载在多孔碳上。S空位与N/F原子为高浓度单原子Sb提供了配位环境，防止其聚集，极大提高了原子利用率。ZnIn₂S₄/C的高比表面积为单原子Sb的有效负载和OER/ORR反应提供了大量的活性位点。具有3D导电结构的PC提高了材料的导电性和的稳定性。这项研究为一步法合成具有高浓度金属单原子、非金属原子掺杂以及空位的复合材料提供了重要启示，可应用到其他电催化剂以及能源材料的制备中。

【数据概览】

Fig. 1. The illustration of the preparation process of (a) Sb_SANF-ZnIn₂S_4-x/PC.  Scanning electron microscopy (SEM) images of (b) ZnIn₂S₄, (c) PC, (d) ZnIn₂S₄/PC, and (e) Sb_SANF-ZnIn₂S_4-x/PC. The TEM images of (f) ZnIn₂S₄, (g) PC, (h) ZnIn₂S₄/PC, and (i) Sb_SANF-ZnIn₂S_4-x/PC. (j) SAED diffraction pattern, (k) HRTEM image,  (l) inverse FFT lattice image, (m) lattice spacing, and (n) mapping of Sb_SANF-ZnIn₂S_4-x/PC. The water contact angles of Sb_SANF-ZnIn₂S_4-x/PC and ZnIn₂S_4-x/PC.

Fig. 2. (a) X-ray diffraction (XRD) patterns of Sb_SANF-ZnIn₂S_4-x/PC，ZnIn₂S₄ and PC. The (b) BET and (c) EPR of Sb_SANF-ZnIn₂S_4-x/PC. XPS peaks of (d) Zn 2p, (e) S 2p, and (f) Sb 3d for Sb_SANF-ZnIn₂S_4-x/PC. (g) HAADF-STEM of Sb_SANF-ZnIn₂S_4-x/PC. (h) Sb K-edge XANES spectra and corresponding FT EXAFS for Sb_SANF-ZnIn₂S_4-x/PC and other materials. WT contour plots (j) Sb₂O₃, (k)Sb_SANF-ZnIn₂S_4-x/PC, and (l) Sb foil.

Fig. 3. (a) Diagram of OER. (b) Polarization curves, (c) Tafel slopes, and (d) specific values in OER of Sb_SANF-ZnIn₂S_4-x/PC, RuO₂, ZnIn₂S₄/PC and ZnIn₂S₄. (e) CV curves and (f) relative electrochemically active surface area of Sb_SANF-ZnIn₂S_4-x/PC and other references in 1.0 M KOH. (g) The EIS of Sb_SANF-ZnIn₂S_4-x/PC, RuO₂, ZnIn₂S₄/PC and ZnIn₂S_4. (h) Amount of gas measured and calculated of the Sb_SANF-ZnIn₂S_4-x/PC. (i) Chronoamperometric stabilities, and (j) polarization curves of before and after cycling stability of of the Sb_SANF-ZnIn₂S_4-x/PC in OER.

Fig. 4. (a) Diagram of ORR. (b) Polarization curves and (c) corresponding Tafel slope in ORR of Sb_SANF-ZnIn₂S_4-x/PC, Pt/C, ZnIn₂S₄/PC, and ZnIn₂S₄. (d) Specific values in ORR of Sb_SANF-ZnIn₂S_4-x/PC，RuO₂, ZnIn₂S₄/PC and ZnIn₂S₄. (e) LSV curves at different rotating speeds and (f) the corresponding Koutecky–Levich plots at different rpm. (g) The EIS of Sb_SANF-ZnIn₂S_4-x/PC，Pt/C, ZnIn₂S₄/PC, and ZnIn₂S₄. (h) Polarization curves before and after 1000th tests. (i) The chronoamperometric stabilities of the Sb_SANF-ZnIn₂S_4-x/PC in ORR (the inset is the SEM image of Sb_SANF-ZnIn₂S_4-x/PC after cycling). (j) The overall polarization curves of catalysts within the ORR and OER potential window. (k) Potential gaps between E_1/2 for ORR and E_j=10 for OER for all electrocatalysts. (l) Comparison of bifunctional activities in this work with representative electrocatalysts in references. 

Fig. 5. (a) Diagram of the freestanding air cathode. (b) OCV curves, (c) Discharge polarization and power density curves, (d) discharge curves, (e) specific capacity, and (f) comparative charge-discharge stability of battery tests under different bending states. (g) Galvanostatic discharge/charge cycling curves of Sb_SANF-ZnIn₂S_4-x/PC as air cathode. (h, i) Charging the mobile phone with ZAB.

【成果启示】

在这项研究中，我们利用了离子液体使用在ZnIn₂S₄/PC中掺入同时掺入了N/F原子和硫空位，和Sb金属单原子。由于高负载的金属单原子Sb有着优异的催化性能和原子利用率，使得Sb_SANF-ZnIn₂S_4-x/PC在OER/ORR/ZAB中均有着优异的性能。DFT计算显示，金属单原子Sb，N/F原子和硫空位的协同效应可以调节ZnIn₂S₄/PC的电子结构并降低中间产物在OER/ORR过程中的能垒，对提高催化性能是有益的。因此，这种设计提供了一种简单的策略在基底中同时掺入了N/F原子，硫空位和高负载量的Sb单原子，为进一步提高OER/ORR的催化效率提供了新的思路。