Enriched Se vacancies engineering of RuSe2 induced by low-valence Cu doping for promoting hydrogen evolution and coupling power generation

Heteroatom doping and vacancy engineering play vital roles in designing a high-activity electrocatalyst . Herein, we proposed a novel enriched Se vacancies engineering of the promising ruthenium chalcogenide of RuSe 2 induced by low-valence Cu doping for promoting hydrogen evolution reaction (HER) electrocatalysis in alkaline media. The Cu-doped RuSe 2 with enriched Se vacancies supported on graphitized carbon (Cu-RuSe 2 @C) was synthesized by a simple one-step selenization of bimetallic MOF precursor of Ru/Cu-BTC (1,3,5-benzenetricarboxylic acid) polyhedra. Compared to the Cu(Ⅱ)-dominant doped RuSe 2 (Cu Ⅱ/Ⅰ -RuSe 2 @C) with deficient Se vacancies, the proposed Cu(Ⅰ)-dominant doped RuSe 2 (Cu Ⅰ/Ⅱ -RuSe 2 @C) with enriched Se vacancies exhibited significantly improved electrocatalytic activity, which was potentially derived from the created electron-deficient Ru δ+ and Se ν− sites induced by low-valence Cu doping. Specifically, Cu Ⅰ/Ⅱ -RuSe 2 @C needed only 40 mV overpotential to drive a HER current density of 10 mA cm −2 , comparable to commercial Pt/C (38 mV) and much lower than those of Cu Ⅱ/Ⅰ -RuSe 2 @C (93 mV) and RuSe 2 @C (362 mV). Furthermore, an alkaline Zn-H 2 O fuel cell with a Cu Ⅰ/Ⅱ -RuSe 2 @C cathode was integrated to demonstrate its potential applications, which delivered a maximum power density of 15.1 mW cm −2 and specific capacitance of 660 mAh g −1 with good stability. Two series-connected alkaline Zn-H 2 O cells acted as a chemical energy converter for simultaneous electricity generation and hydrogen coproduction by driving the coupled water splitting.