Decoupling the Impact of Key Industrial Operating Conditions on the Stability of CoP Alloy Catalysts for the Alkaline Hydrogen Evolution Reaction

Abstract Green hydrogen, as a key energy carrier in pursuit of carbon neutrality, has advantages such as high energy density and zero carbon emissions. Transition metal phosphides (TMPs) are considered potential catalysts for producing green hydrogen through water electrolysis due to their unique electronic structures and excellent conductivities. However, TMPs face challenges such as activity degradation and unclear stability degradation mechanisms under actual operating conditions. Herein, CoP was selected as a model electrocatalyst to systematically evaluate its durability under decoupled key industrial conditions. The influence of various parameters such as soaking time, temperature, electrolyte concentration, current density, and reverse current on the structure of CoP and the performance of water electrolysis was revealed. Under the specific experimental protocols employed in this study, the results showed that the effect of reverse current was the most significant, leading to changes in structural morphology, driving irreversible structural phase transition of CoP to form CoOOH, and resulting in a large amount of P dissolution, structure collapse, and reconstruction. High electrolyte concentration is the second major factor limiting stability, as the high concentration of OH– adsorbs on the material surface and is difficult to desorb, suppressing charge transfer and slowing down reaction kinetics. In contrast, current density has a relatively minor effect on CoP activity and stability. This work highlights the crucial role of conducting accelerated degradation tests under real working conditions, providing insights and theoretical guidance for designing efficient electrocatalysts for industrial applications.