*Article* **Synthesis of Self-Supported Cu/Cu3P Nanoarrays as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction**

**Rui Dang 1,\* , Xiufeng Xu <sup>2</sup> , Mengmeng Xie <sup>2</sup> and Jian Liu 2,\***


**Abstract:** Owing to the energy crisis and environmental pollution, it is essential to develop cheap, environmentally friendly and sustainable energy to replace noble metal electrocatalysts for use in the hydrogen evolution reaction (HER). We report herein that a Cu/Cu3P nanoarray catalyst was directly grown on the surfaces of Cu nanosheets from its Cu/CuO nanoarray precursor by a lowtemperature phosphidation process. In particular, the effects of phosphating distance, mass ratio and temperature on the morphology of Cu/Cu3P nanoarrays were studied in detail. This nanoarray, as an electrocatalyst, displays excellent catalytic performance and long-term stability in an acid solution for electrochemical hydrogen generation. Specifically, the Cu/Cu3P nanoarray-270 exhibits a low onset overpotential (96 mV) and a small Tafel slope (131 mV dec−<sup>1</sup> ).

**Keywords:** Cu/Cu3P nanoarrays; Cu nano-substrates; electrocatalyst; HER

**Citation:** Dang, R.; Xu, X.; Xie, M.; Liu, J. Synthesis of Self-Supported Cu/Cu3P Nanoarrays as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction. *Catalysts* **2022**, *12*, 762. https://doi.org/10.3390/ catal12070762

Academic Editors: Yongjun Ji, Liwen Xing and Ke Wu

Received: 27 May 2022 Accepted: 7 July 2022 Published: 9 July 2022

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