Photoelectrocatalytic Utilization of CO 2 : A Big Show of Si-based Photoelectrodes.

CO 2 is a greenhouse gas that contributes to environmental deterioration; however, it can also be utilized as an abundant C1 resource for the production of valuable chemicals. Solar-driven photoelectrocatalytic (PEC) CO 2 utilization represents an advanced technology for the resourcing of CO 2 . The key to achieving PEC CO 2 utilization lies in high-performance semiconductor photoelectrodes. Si-based photoelectrodes have attracted increasing attention in the field of PEC CO 2 utilization due to their suitable band gap (1.1 eV), high carrier mobility, low cost, and abundance on Earth. There are two pathways to PEC CO 2 utilization using Si-based photoelectrodes: direct reduction of CO 2 into small molecule fuels and chemicals, and fixation of CO 2 with organic substrates to generate high-value chemicals. The efficiency and product selectivity of PEC CO 2 utilization depends on the structures of the photoelectrodes as well as the composition, morphology, and size of the catalysts. In recent years, significant and influential progress has been made in utilizing Si-based photoelectrodes for PEC CO 2 utilization. This review summarizes the latest research achievements in Si-based PEC CO 2 utilization, with a particular emphasis on the mechanistic understanding of CO 2 reduction and fixation, which will inspire future developments in this field.