Facile synthesis of CeO2 decorated Co4N nanoparticles as highly active and durable electrocatalyst for oxygen evolution reaction

초록

Growing concerns about depletion of fossil fuels and global warming demand the exploration of eco-friendly and efficient energy sources. Recently, hydrogen gas has been considered as a promising candidate for future energy source owing to its environmental friendliness and high energy density. Electrochemical water splitting, involving cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER), is an ideal technology for hydrogen production without any other impurities such as carbon dioxide. Unfortunately, the overall efficiency of water electrolysis is seriously limited by the sluggish kinetics and large overpotential of OER due to the energetically unfavorable four-electron reaction pathway. Therefore, the development of efficient and durable OER electrocatalyst is essential to decrease the reaction energy barrier for OER and enhance the performance of the overall water electrolysis. Among the noble metal-free materials such as transition metal oxides, sulfides, phosphides, nitrides etc., the transition metal nitrides (TMNs) showed promising electrocatalytic activity toward the OER. The TMNs have anti-corrosion stability in alkaline solution and high electrical conductivity due to their metallic feature. Furthermore, the nitrogen atoms in TMNs induce expansion of metal lattice and modify transition metal d-band structure, thereby shifting their d-band center into the optimal energy state for OER. Despite the noticeable progress in TMNs-based electrocatalysts, their unsatisfactory OER performance need to be further improved because of inferior redox reaction kinetics of TMNs. To boost electrocatalytic OER activity of TMNs, construction of heterostructure with other species which has rich redox properties can be adopted as efficient strategy.