LSPR-enhanced photocatalytic N2 fixation over Z-scheme POMOF-derived Cu/WO2 modified C-BiOBr with multiple active sites

Abstract

The conception and production of nitrogen-fixing photocatalysts with efficient charge separation rates and multiple active sites have been the focus of research. In this paper, we prepared Cu/WO2 nanoparticles by high-temperature calcination of polyoxometalate based open frameworks (POMOFs) and then anchored them in interstitial carbon-doped BiOBr using a one-step hydrothermal method to obtain a novel Z-scheme Cu/WO2/C-BOB ternary heterostructure. The ammonia generation rate over the Cu/WO2/C-BOB heterojunction is 477.5 μmol g-1 h-1 in deionized water without any sacrificial reagents under full solar spectrum, which is nearly 6.1 times greater than pure BiOBr. The synergistic effect of heteroatom doping, Z-scheme heterojunction and oxygen vacancies inhibits the recombination of photogenerated carriers and maintains their maximum redox capacity, providing more reaction sites and significantly improving the photocatalytic performance. In addition, the localized surface plasmon resonance effect (LSPR) of Cu NPs enhances light absorption and motivates high-energy hot electrons to produce additional oxygen vacancies. Meanwhile, we explored the charge transfer pathways and possible reaction mechanisms of the heterojunctions through experimental characterization and DFT calculations, which provided a new idea to synergistically utilize the LSPR effect and Z-scheme heterostructures for the design of efficient photocatalysts.