Electrochemically Modified Mn₂P₄O₁₂ as an Emerging Catalyst for Oxygen Evolution Reaction

Water splitting is a promising and sustainable technology that can address energy and environmental challenges by producing clean H2 without emissions of harmful pollutants. However, alkaline water oxidation is the most relevant process at the industrial level, and it faces obstacles due to unfavorable thermodynamics and high overpotential. The search for new environmentally friendly materials with high activity and low cost is a significant challenge. Herein, Mn2P4O12 microspheres are synthesized from MnO2 nanosheets via hydrothermal and chemical vapor deposition processes by regulating phosphorization as a new material in water-splitting catalysis. The spherical Mn2P4O12 microstructures act as pre-catalysts and undergo surface reconstruction during electrochemical activation, leading to the formation of beta-MnO2 as the true active phase. Once stabilized, they exhibit outstanding catalytic performance (250 and 510 mV at 10 and 100 mA cm-2 with Tafel slope as low as 40.80 mV dec-1) and stability for more than 32 h at different potentials. The in situ surface reconstruction highlighted by a multi-technique analysis ensures the catalyst's stability and results in efficient catalytic active sites for adsorbed oxygen, which enhances overall performance. This study provides insights into cyclotetraphosphate catalysis and offers a pathway for developing efficient and cost-effective materials for water electrolysis.