Wang Yan-Ni, Yang Zhao-Jin, Yang Dong-Hui, Zhao Li, Shi Xue-Rong, Yang Guocheng, Han Bao-Hang
School of Chemical Engineering, Advanced Institute of Materials Science, Changchun University of Technology, Changchun 130012, China.
CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
ACS Appl Mater Interfaces. 2021 Feb 24;13(7):8832-8843. doi: 10.1021/acsami.0c22336. Epub 2021 Feb 15.
The design and synthesis of low-cost and efficient bifunctional electrocatalysts for water splitting are critical and challenging. Hereby, a bimetallic phosphide embedded in a N and P co-doped porous carbon (FeCoP@NPPC) material was synthesized by using sustainable biomass-derived N- and P-containing carbohydrates and non-noble metal salts as precursors. The obtained material exhibits good catalytic activities in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The bimetallic alloy phosphide (FeCoP) is the active site for electrocatalysis. Theoretical calculation indicates that the sub-layer Fe atoms and top-layer Co atoms in FeCoP exhibit a synergistic effect for enhanced electrocatalytic performance. The carbon matrix around the FeCoP can prevent the corrosion during the catalytic reactions. The hierarchically porous structure of the FeCoP@NPPC material can promote the transfer of electrons and electrolyte, and increase the contact area of the active sites and electrolytes. N- and P-containing functionalities improve the wetting and conductivity properties of the porous carbon. Due to the synergistic effects, FeCoP@NPPC requires a low overpotential of 114 and 150 mV at the current density of 10 mA cm for HER in 0.5 M HSO and 1.0 M KOH, and an overpotential of 236 mV for OER in 1.0 M KOH solution, which are much lower than those of FeP@NPPC and CoP@NPPC. Based on the density functional theory calculation, FeCoP yields the smallest Gibbs free energy change of rate-determining step among the samples, which leads to better electrochemical performances. In addition, when FeCoP@NPPC was used as a bifunctional catalyst in water splitting, the electrolyzer needed a low voltage of 1.60 V to deliver the current density of 10 mA cm. Furthermore, this work provides a strategy for preparing sustainable, stable, and highly active electrocatalysts for water splitting.
设计和合成用于水分解的低成本、高效双功能电催化剂至关重要且具有挑战性。在此，通过使用可持续的生物质衍生含氮和磷的碳水化合物以及非贵金属盐作为前驱体，合成了一种嵌入氮和磷共掺杂多孔碳中的双金属磷化物（FeCoP@NPPC）材料。所获得的材料在析氢反应（HER）、析氧反应（OER）和整体水分解中表现出良好的催化活性。双金属合金磷化物（FeCoP）是电催化的活性位点。理论计算表明，FeCoP中的亚层铁原子和顶层钴原子表现出协同效应，以增强电催化性能。FeCoP周围的碳基体可以防止催化反应过程中的腐蚀。FeCoP@NPPC材料的分级多孔结构可以促进电子和电解质的转移，并增加活性位点与电解质的接触面积。含氮和磷的官能团改善了多孔碳的润湿性和导电性。由于协同效应，在0.5 M H₂SO₄中HER的电流密度为10 mA cm⁻²时，FeCoP@NPPC所需的过电位为114 mV，在1.0 M KOH中为150 mV，在1.0 M KOH溶液中OER的过电位为236 mV，远低于FeP@NPPC和CoP@NPPC。基于密度泛函理论计算，FeCoP在样品中速率决定步骤的吉布斯自由能变化最小，这导致了更好的电化学性能。此外，当FeCoP@NPPC用作水分解的双功能催化剂时，电解槽需要1.60 V的低电压来提供10 mA cm⁻²的电流密度。此外，这项工作为制备用于水分解的可持续、稳定和高活性电催化剂提供了一种策略。
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