Single-step AACVD growth of wrinkled RhCo alloy thin films on titanium foam as active and durable electrocatalysts for acidic hydrogen evolution

Durable and cost-effective electrocatalysts used for the hydrogen evolution reaction (HER) under acidic conditions are essential for advancing proton exchange membrane (PEM) water electrolysis. Herein, we report the direct deposition of pristine Co, pristine Rh, and binary RhCo alloy thin-film electrocatalysts on porous titanium foam via a single-step aerosol-assisted chemical vapor deposition process. Electrochemical measurements in 0.5 M H₂SO₄ show that the wrinkled mesoporous RhCo alloy exhibits significantly enhanced HER activity compared to pristine Rh and Co films. The optimized RhCo catalyst, achieves a low overpotential of −190 mV at −1000 mA cm−2, a small Tafel slope of 31 mV dec−1 and stable operation at current densities of −25, −50, and −100 mA cm−2 over 100 h. Importantly, the reduced Rh content, enhanced activity, and better stability of RhCo alloy catalysts improve their economic feasibility for practical PEM water electrolyzer applications.