Alkali metal doped copper-sulfides as a new class electrocatalysts for oxygen evolution reaction

Copper sulfides (CuxS, x = 1 or 2) are extensively used in important reactions, including those involved in catalysis, superconductors, and biosensors. However, their oxygen evolution activity is much lower than that of other transition metal sulfides due to insufficient active sites and low intrinsic activity which limits their applicability in oxygen evolution reactions (OER). Therefore, it is essential to design effective strategies to enhance the OER performance of copper sulfides and understand their catalytic mechanisms. Here, A-Cu-S (A = Li, Na, K) is developed by introducing alkali metal ions (Li/Na/K) into CuxS (x = 1 or 2). Doping the alkali metal ions increases their electrical conductivity and optimizes the oxygenated intermediates' adsorption energy, improving the CuxS (x = 1 or 2) OER performance. The optimum overpotential of NaCu5S3 is 271@20 mA cm−2; much higher than Cu2S (> 450 mV), CuS (∼ 400 mV), and most other copper sulfides (300–400 mV). The improvement in the copper sulfide OER performance shows that the Li/Na/K doping strategy has an important and promising effect on the design of efficient copper sulfide electrocatalysts.