文献速递|东北师范大学ASS:通过Co-MOF衍生的异质结构的共催化促进BiVO4光阳极的光电化学水氧化过程

第一作者：Dan Wang

通讯作者：张昕彤 教授

通讯单位：东北师范大学

DOI:10.1016/j.apsusc.2023.156710

在本文中，我们提出了一项比较研究，以评估MOF衍生的异质结构助催化剂对BiVO4光阳极的PEC性能的影响。通过在室温下将原始BiVO4电极浸入MOF前体溶液中，在多孔BiVO4表面原位修饰不同负载时间的Co基MOFs（ZIF-67）。得到的BiVO4-MOF光阳极在氮气（N2）环境中退火，将MOF转化为具有Co-active反应中心的碳基。Co-MOF衍生的OECs明显增强了BiVO4光阳极的PEC性能。光电流密度达到2.32 mA-cm-2（1.23 V vs RHE），是BiVO4光阳极0.88 mA-cm-2的2.64倍，并且起始电位负向移动了200 mV。与纯粹的MOF催化剂相比，由于碳基体在BiVO4到Co-active中心的电荷转移过程中具有良好的导电性，因此MOF衍生的催化剂显示出更高的电荷转移效率和更低的电荷转移电阻率。这项工作可能对通过平衡表面活性点数量和电荷转移能力来促进光阳极表面的电荷转移过程提出了新的见解。

Fig. 1. The SEM images of (a) as-prepared porous BiVO4 photoelectrode, (b) BiVO4 immersed in MOF precursor solution for 30 min (BiVO4-MOF), and (c) BiVO4 immersed in MOF solution for 30 min followed by annealing in N2 gas (BiVO4-MOF-N2). SEM images with higher magnification of (d) BiVO4, (e) BiVO4-MOF, and (f) BiVO4-MOF-N2 photoelectrodes.Fig. 2. Bi, V, O, Co, C, and N elemental mapping of BiVO4-MOF-N2 photoelectrode.Fig. 3. (a) XRD patterns, (b) Raman spectra, and (c) light absorption spectra of pristine BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 photoelectrodes. (d) Light absorption spectra of Co-MOF powder and that after annealing in the N2 atmosphere (Co-MOF-N2).Fig. 4. (a), (b), and (c) are TEM images of BiVO4-MOF with different magnifications. (d), (e), and (f) are TEM images of BiVO4-MOF-N2 electrodes with different magnifications; (g) and (h) are enlarged HRTEM images in Fig. 4 (f).Fig. 5. XPS spectra of (a) Bi, (b) V, and (c) O elements in BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes.Fig. 6. XPS spectra of (a) C, (b) N, and (c) Co elements in BiVO4-MOF, and BiVO4-MOF-N2 electrodes.Fig. 7. (a) I-V curves of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes under the illumination of AM 1.5G with the scan rate of 10 mV·s−1; (b) The current density at 1.23 V vs RHE and onset potential of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes; (c) Photocurrent vs time curves measured under chopped light illumination at a time interval of 10 s; (d) The ratio of Ispike-steady and Isteady for electrodes of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes.Fig. 8. (a) The I-V curves of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes measured in the electrolyte of 0.5 M Na2SO4 with and without 0.1 M Na2SO3 as the hole scavenger. (b) The surface charge transfer efficiencies of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes. (c) Impedance spectra of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes. The inset in Fig. 8c is the equivalent circuit. (d) The fitted charge transfer resistivities of BiVO4, BiVO4-MOF, and BiVO4-MOF-N2 electrodes.Fig. 9. The Kelvin probe test of Au, BiVO4, MOF and MOF-N2 samples. (b) The calculated work function of BiVO4, MOF, and MOF-N2 samples. The schematic illustration of the energy band for BiVO4 and MOF-N2 (c) at equilibrium after contact, and (d) under the illumination.Fig. 10. (a) The I-V curves of BiVO4, BiVO4-N2, and BiVO4-MOF-N2 photoanodes with different deposition time in MOF precursor solution measured under irradiation of AM 1.5G simulated solar light. (b) Histogram of current densities of different samples at 1.23 V vs RHE. (c) The enlarged I-V curves in Fig. 10 (a). (d) Histogram of onset potential of different samples at 1.23 V vs RHE.