Construction of a direct Z-scheme Mn0.5Cd0.5S/CoTiO3 heterojunction with enhanced photocatalytic nitrogen fixation performance

Abstract

The exploration and design of highly efficient and robust photocatalysts composed of earth-abundant materials for ambient photocatalytic N2 fixation to ammonia remains a significant challenge. Here, we have fabricated a stable and highly efficient direct Z-scheme Mn0.5Cd0.5S/CoTiO3 heterostructure for N2 fixation by depositing Mn0.5Cd0.5S nanoparticles on CoTiO3 surface. Under ambient conditions, the optimized Mn0.5Cd0.5S/CoTiO3 heterojunction achieved a significant NH3 production rate of 121.9 μmol g-1h−1 without cocatalyst modification, representing a 5.1- and 5.9-fold increase over pristine Mn0.5Cd0.5S and CoTiO3, respectively, and also exceeding most previously reported photocatalytic systems. The significant improvement in ammonia production primarily results from the Z-scheme charge transfer path between the Mn0.5Cd0.5S and CoTiO3 components, which enables effective separation of photoinduced carriers while maintaining their robust redox capacity, thus dramatically boosting ammonia generation performance. This research may provide new insights for advancing other alternative Z-scheme photocatalytic systems with remarkable stability and exceptional efficiency in N2 fixation.