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Heterostructure iron selenide/cobalt phosphide films grown on nickel foam for oxygen evolution
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2023-03-29 , DOI: 10.1039/d2ta09817b
Shuling Liu 1 , Yichuang Xing 1 , Zixiang Zhou 1 , Yifan Yang 1 , Yvpei Li 1 , Xuechun Xiao 1 , Chao Wang 1
Affiliation  

Construction of heterostructures is an effective strategy for improving electrocatalytic activity. Here, heterostructure iron selenide/cobalt phosphide films (FeSe/Co2P) are synthesized on nickel foam (NF) substrates. Crystalline Co2P is grown on NF (Co2P/NF) by a solvothermal method, and an amorphous FeSe layer is electrodeposited on Co2P/NF. The formation of the heterointerface is confirmed by high-resolution transmission electron microscopy. For the OER in 1 M KOH, FeSe/Co2P/NF only requires overpotentials of 235 mV and 265 mV to reach 10 mA cm−2 and 50 mA cm−2 current densities, respectively, with a Tafel slope of 65.6 mV dec−1. Compared with Co2P/NF, the high OER activity of FeSe/Co2P/NF does not originate from the higher electrochemically active surface area, but from enhanced OER activity per Co site. This is caused by the charge redistribution induced by the heterostructure that alters the adsorption energy of the hydroxyl group, and that leads to more facile OER kinetics as indicated by the reduced charge transfer resistance, lower Tafel slope and lower apparent activation energy. At the FeSe/Co2P/NF surface, the lattice oxygen evolution mechanism dominates, while the adsorbate evolution mechanism prevails at the Co2P/NF surface. The altered mechanism is probably caused by the increased pKa of the CoIV–OH or CoIV–OH2 structure in FeSe/Co2P/NF that favors the decoupled proton–electron transfer process. FeSe/Co2P/NF also exhibits good long-term durability, and transformation of surface metal selenides and phosphides to oxides and (oxy)hydroxides is observed after the long-term OER.

中文翻译:

在泡沫镍上生长的异质结构硒化铁/磷化钴薄膜用于析氧

构建异质结构是提高电催化活性的有效策略。在这里,异质结构硒化铁/磷化钴薄膜 (FeSe/Co 2 P) 在泡沫镍 (NF) 基板上合成。通过溶剂热法在NF(Co 2 P/NF)上生长结晶Co 2 P,并在Co 2 P / NF电沉积非晶FeSe层。高分辨率透射电子显微镜证实了异质界面的形成。对于 1 M KOH 中的 OER,FeSe/Co 2 P/NF 仅需要 235 mV 和 265 mV 的过电势即可分别达到 10 mA cm -2和 50 mA cm -2电流密度,Tafel 斜率为 65.6 mV dec −1. 与 Co 2 P/NF 相比,FeSe/Co 2 P/NF的高 OER 活性并非源于较高的电化学活性表面积,而是源于每个 Co 位点的 OER 活性增强。这是由异质结构引起的电荷重新分布引起的,异质结构改变了羟基的吸附能,并导致更容易的 OER 动力学,如电荷转移电阻降低、塔菲尔斜率降低和表观活化能降低所示。在FeSe/Co 2 P/NF表面,晶格氧析出机制占主导地位,而吸附物析出机制在Co 2 P/NF表面占主导地位。改变的机制可能是由Co 的p K a增加引起的FeSe/Co 2 P/NF 中的IV –OH 或 Co IV –OH 2结构有利于解耦质子-电子转移过程。FeSe/Co 2 P/NF 也表现出良好的长期耐久性,并且在长期 OER 后观察到表面金属硒化物和磷化物向氧化物和(氧)氢氧化物的转变。
更新日期:2023-03-29
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