Abstract

H2 has become one of the most attractive alternatives to replace fossil fuels in clean energy production, but large-scale production remains a challenge. A key step toward this goal is to develop new efficient electrocatalysts for H2 production. This work presents a new mixed metal oxides-decorated CNT paste electrode (MMO@C), which is highly electrocatalytic, for use in the hydrogen evolution reaction (HER). MMO@C is synthesized by a solvothermal method and used as an easy-to-prepare paste electrode. XPS and X-ray analysis indicate that the electrocatalyst corresponds to a mixed surface of Ga2O3-CuO-Cu2O-Cu(OH)2@C. The MMO@C electrocatalyst shows a positive Eo of 0.12 V vs. RHE at ?10 mA cm?2 towards the HER in a neutral medium. In neutral and alkaline media, the presence of Ga2O3 facilitates the reduction of CuO to Cu(I) species, which is followed by the formation of Cu(s) active sites. Therefore, the excellent electrocatalytic performance toward the HER in a neutral medium is attributed to the synergistic effect between gallium and copper oxides on the electrode surface. The prominent H2 production using MMO@C electrocatalyst is 1.31 × 10?2 mol cm?2, with a turnover number (TON) of 39,423, a turnover frequency (TOF) of 13,141 h?1, and a faradaic efficiency (FE) of 94.3%. Although the Tafel slope reveals slow reaction kinetics, the outstanding onset potential allows for the coupling of the electrocatalyst to renewable energy production systems, making it an attractive candidate for producing green H2 and for application in membrane water electrolyzers. © 2025 by the authors.