Herein, a multifunctional binary nickel–copper-modified MXene on nickel foam was synthesized and employed as an electrode material for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), overall water splitting and supercapacitors. This work focused on the synthesis of a binder-free electrode, where 2-dimensional MXene was electrodeposited onto nickel foam, followed by the electrodeposition of nickel–copper (Ni_xCu_yMX–NF) bimetallic heterostructures using the co-electrodeposition or sequential electrodeposition technique. Compared to the bare nickel foam and electrodeposited MXene-based nickel foam, the co-deposition of Ni–Cu resulted in agglomerated structures and good electrocatalytic activity towards HER, OER and supercapacitor application. Alternatively, it is interesting to note that owing to the uniform coverage of copper particles on the surface of nickel on the electrodeposited MXene/nickel foam (MX–NF), the electrode (NiCuMX–NF) with copper particles as the top layer generated by sequential electrodeposition was superior to the other electrocatalysts. The combined effects of MXene and binary nickel–copper on the nickel foam support enhanced the catalytic activity of the composite in energy conversion for electrochemical water splitting, exhibiting a current density of 10 mA cm⁻² with a Tafel slope of 104 mV dec⁻¹ at an overpotential (η) of 111.14 mV for hydrogen evolution reaction (HER) and Tafel slope of 146.1 mV dec⁻¹ at an overpotential (η) of 185.2 mV for oxygen evolution reaction (OER) in alkaline medium. Furthermore, the potential of NiCuMX–NF for energy storage as an electrode material was investigated together with other synthesised electrocatalysts, which was shown to be a good specific capacitance supercapacitor with the cyclic retention of 70.4% after 5000 cycles. Thus, the results of this study highlight that the prepared electrocatalyst can be applied as a multifunctional electrode for energy conversion and storage devices.

中文翻译：

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二元 Ni-Cu 纳米复合材料改性 MXene 装饰的 3D 镍泡沫，用于有效的整体水分解和超级电容器应用

在此，合成了泡沫镍上的多功能二元镍-铜改性MXene，并将其用作析氢反应（HER）、析氧反应（OER）、整体水分解和超级电容器的电极材料。这项工作的重点是合成无粘合剂电极，其中将二维 MXene 电沉积到镍泡沫上，然后使用共电沉积或顺序电沉积镍铜 (Ni _x Cu _y MX-NF) 双金属异质结构电沉积技术。与裸泡沫镍和电沉积 MXene 基泡沫镍相比，Ni-Cu 共沉积产生团聚结构，并且对 HER、OER 和超级电容器应用具有良好的电催化活性。另外，值得注意的是，由于电沉积 MXene/泡沫镍 (MX–NF) 上的镍表面上铜颗粒均匀覆盖，因此以铜颗粒作为顶层的电极 (NiCuMX–NF) 生成顺序电沉积优于其他电催化剂。MXene和二元镍-铜在泡沫镍载体上的综合作用增强了复合材料在电化学水分解能量转换中的催化活性，表现出10 mA cm ^{-2的电流密度和104 mV dec -1}的塔菲尔斜率在碱性介质中，析氢反应 (HER) 的过电势( η ) 为 111.14 mV，析氧反应 (OER) 的过电势 ( η ) 为 146.1 mV dec ^{-1 。}此外，与其他合成电催化剂一起研究了NiCuMX-NF作为电极材料的储能潜力，结果表明它是一种良好的比电容超级电容器，5000次循环后循环保留率为70.4%。因此，本研究的结果表明，所制备的电催化剂可以用作能量转换和存储装置的多功能电极。