Dual plasmonic coupling effect in Bi/vacancy-rich Bi2WO6 heterojunction for selective CO2 photoreduction to CH4

Abstract

Low-cost plasmonic semiconductors with high density of free carriers have attracted increasing attention in photocatalytic CO2 reduction (PCR), since they display the localized surface plasmon resonance (LSPR) to improve the light-harvesting and produce hot electrons to boost the PCR activity. However, the produced hot electrons in plasmonic semiconductors are easily suppressed to limit the enhancement of the PCR performance. Herein, the dual plasmonic coupling system of Bi nanoparticles/vacancy-rich Bi2WO6 nanosheets (BWO-Vo-Bi) is designed and constructed. An intense plasmonic coupling induced by metal Bi and plasmonic semiconductor of vacancy-rich Bi2WO6 is formed, thus contributing to a strong full-spectrum solar absorption and fast charge transfer in BWO-Vo-Bi heterojunction. The significant enhancement of light absorption and charge movement further accelerates the generation of high-energy hot electrons and extends the lifetime of photogenerated electrons, thereby yielding a high CH4 evolution rate of 20.36 μmol g-1 h−1 with a selectivity of 93.0 % in BWO-Vo-Bi under light irradiation without sacrificial agents, which is 55 times higher than that of Bi2WO6. This work provides a new strategy for the development of high-performance photocatalysts for CO2 reduction through dual plasmonic coupling.