Effect of gas mass transfer on hydrogen production at ampere-level current densities

Water electrolysis driven by renewable energy sources is a green, sustainable hydrogen production method. However, industrial hydrogen production via water electrolysis is challenged by its high cost, high energy consumption and low conversion efficiency. It is urgently necessary to develop efficient, stable, and inexpensive electrocatalysts at ampere-level current densities. In this study, we mainly reveal the gas mass transfer effect under ampere-level current densities during water electrolysis. Typically, we synthesize FeNi-MOF through a simple method. Meanwhile, the Fe₁Ni₁P-C electrocatalyst is synthesized through phosphidation of the FeNi-MOF precursor. The Fe₁Ni₁P-C electrocatalyst demonstrates an excellent electrocatalytic activity in alkaline electrolyte: for the hydrogen evolution reaction (HER), η₁₀ = 118.2 mV, η₁₀₀₀ = 301.2 mV, and Tafel slope = 72.44 mV dec⁻¹; for the oxygen evolution reaction (OER), η₁₀ = 90.8 mV, η₁₀₀₀ = 332.3 mV, and Tafel slope = 68.69 mV dec⁻¹. Moreover, Fe₁Ni₁P-C exhibits a high stability at a large current density (110 h @ 1000 mA cm⁻²). Density functional theory (DFT) calculations confirm that the components of Fe₁Ni₁P-C exhibit gas-phobic behavior toward H₂ and O₂ molecules, effectively suppressing gas bubble accumulation on electrode surfaces and thereby facilitating continuous and steady reactions. This study presents a material design method that effectively enhances stability under high current density through the presence of a gas-repelling structure.