The In-situ Growth of Ru Modified CoP Nanoflakes on Carbon Clothes as Efficient Electrocatalysts for HER**

Graphical Ru-CoP/CC electrocatalyst for hydrogen evolution was synthesized through simple in-situ hydrothermal and gas phosphatized treatments, which only needs 44 mV to reach 10 mA cm −2 , exceeding many reported electrocatalysts. Meanwhile, the reason and the result of electrons redistribution after Ru doping were deeply investigated. Exploring highly efficient, durable and low-cost catalysts for hydrogen evolution reaction (HER) is crucial to promoting the development of electrochemical water splitting systems but remains challenging. In this work, the Ru-modified CoP nanoflakes on carbon clothes (Ru-CoP/CC) are fabricated via an in-situ hydrothermal method, followed by low-temperature phosphatized treatments. According to X-ray photoelectron spectroscopy (XPS) measurements, the Ru doping induces the electron deviation from Ru to Co−P, and makes Co ions be an electron-rich state. It is revealed that the introduction of Ru can effectually reconstruct the electron coordination environment of Co−P. The resultant Ru-CoP/CC catalyst shows outstanding HER performance with an ultralow overpotential of 45 mV at 10 mA cm −2 . Moreover, the obtained catalyst exhibits long-term durability at 20 mA cm −2 for 20 h in the alkaline solution. This work opens a new avenue to lower the usage of noble metal in electrocatalyst and helps to developing a high-performance electrocatalyst for HER.