Surface/interface regulation of NiMo-based catalysts for durable anion exchange membrane water electrolysis under intermittent operation conditions

Encouraging progress has been made in boosting the hydrogen evolution reaction (HER) activity of NiMo-based catalysts. However, their practical application in anion exchange membrane water electrolysis (AEMWE) systems still faces the obstacle of stability, especially under intermittent operation conditions. Here, we developed an innovative electrodeposition method to regulate the surface/interface of NiMo-based catalysts by simultaneously adding a P source and an ammonium additive to the deposition precursor solution. The best-performing NiMoP-A catalyst exhibits excellent HER performance with an overpotential of only 175 mV at a current output of 1000 mA/cm2, which can be attributed to the improved specific surface active sites, enhanced hydrogen binding energy, and optimized OH binding energy. Furthermore, when paired with a bare Ni foam anode in AEMWE, the device with NiMoP-A cathode exhibits ultra-high stability with almost no decay during the accelerated stress testing involving 10k startup/shutdown cycles. Such stability originates from the synergistic effect of P-doping and ammonium additives, which jointly modulate the surface/interface of the catalyst, thereby enhancing both mechanical and chemical stability. This study provides key insights into enhancing electrode stability in AEMWE under intermittent operation conditions.