Impact of Phosphide-Phosphate Ratio on NiCoP Catalysts for Hydrogen Evolution in Anion Exchange Membrane Water Electrolysis

초록

Alkaline and anion exchange membrane water electrolysis (AEMWE) presents a promising approach for hydrogen production. However, the slow kinetics of the alkaline hydrogen evolution reaction (HER) remains a significant challenge. This study aimed to enhance HER activity by optimizing transition metal-phosphorus compound catalysts, including Ni, Co, NiCo, NiP, CoP, and NiCoP. Their surface structure, crystallinity, electrochemical properties, and HER performance were meticulously studied. Among the catalysts, Ni28Co62P10 exhibited exceptional HER performance, achieving a low overpotential of 48 mV at a current density of -10 mA cm-2 in 1 M KOH. X-ray photoelectron spectroscopy analysis revealed that an optimal 1:1 balance of phosphate to phosphide is critical for achieving efficient HER. These findings emphasize the importance of balancing phosphorus species for optimal alkaline HER catalysis. Moreover, Ni28Co62P10 demonstrated excellent durability, maintaining high performance after 5000 cycles. In AEMWE single-cell tests, the catalyst achieved a cell voltage of 1.88 V at 1 A cm-2, surpassing the performance of Ni/Co-based catalysts from previous studies. The NiCoP-based catalysts in this study presented considerable promise for AEMWE systems, paving the way to the development of more efficient and durable catalysts for hydrogen production and advancing hydrogen-based renewable energy technologies.

키워드