Vertically-interlaced NiFeP/MXene electrocatalyst with tunable electronic structure for high-efficiency oxygen evolution reaction

垂直交错且具有可控电子结构的NiFeP/MXene电催化剂用于高效析氧反应

Layered double hydroxides(LDHs)with decent oxygen evolution reaction(OER)activity have been extensively studied in the fields of energy storage and conversion.However,their poor conductivity,ease of agglomeration,and low intrinsic activity limit their practical application.To date,improvement of the intrinsic activity and stability of NiFe-LDHs through the introduction of heteroatoms or its combination with other conductive substrates to enhance their water-splitting performance has drawn increasing attention.In this study,vertically interlaced ternary phosphatised nickel/iron hybrids grown on the surface of titanium carbide flakes(NiFe P/MXene)were successfully synthesised through a hydrothermal reaction and phosphating calcination process.The optimised NiFe P/MXene exhibited a low overpotential of 286 m V at 10 m A cm^(-2) and a Tafel slope of 35 m V dec^(-1) for the OER,which exceeded the performance of several existing NiFe-based catalysts.NiFe P/MXene was further used as a water-splitting anode in an alkaline electrolyte,exhibiting a cell voltage of only 1.61 V to achieve a current density of 10 m A cm^(-2).Density functional theory(DFT)calculations revealed that the combination of MXene acting as a conductive substrate and the phosphating process can effectively tune the electronic structure and density of the electrocatalyst surface to promote the energy level of the d-band centre,resulting in an enhanced OER performance.This study provides a valuable guideline for designing high-performance MXenesupported NiFe-based OER catalysts.

具有良好析氧反应(OER)活性的层状双氢氧化物(LDHs)在储能/转化领域得到了广泛的研究.然而,导电性差、易团聚、本征活性低等特点限制了其实际应用.通过改善NiFeLDHs的本征活性和稳定性(如引入杂原子或与其他导电基质结合)以提高全解水性能,受到越来越多的关注.本文通过水热和煅烧磷化两步反应,成功合成了在碳化钛二维薄片上的垂直交错的三元相磷化镍/铁杂化物(NiFeP/MXene).优化后的NiFe P/MXene在电流密度为10 mA cm^(-2)时仅有286 mV的低过电位和较低的塔菲尔斜率35 mV dec^(-1),超过了许多现有的NiFe基催化剂的性能.进一步将NiFeP/MXene应用于碱性电解质中全解水的阳极,仅需要1.61 V的电池电压就能达到10 mA cm^(-2)的电流密度.密度函数理论(DFT)计算结果表明,无论是MXene还是磷化,都能有效调整电催化剂表面的电子结构和密度,提升d带中心的能级,从而实现对OER性能的提升.该研究为设计高性能的OER催化剂提供了新的思路.