Triazine-COF@Silicon nanowire mimicking plant leaf to enhance photoelectrocatalytic CO₂ reduction to C₂₊ chemicals

Converting CO₂ and water into valuable chemicals like plant do is considered a promising approach to address both environmental and energy issues. Taking inspiration from the structures of natural leaves, we designed and synthesized a novel copper-coordinated covalent triazine framework (CuCTF) supported by silicon nanowire arrays on wafer chip. This marks the first-ever application of such a hybrid material in the photoelectrocatalytic reduction of CO₂ under mild conditions. The Si@CuCTF6 heterojunction has exhibited exceptional selectivity of 95.6% towards multicarbon products (C₂₊) and apparent quantum efficiency (AQE) of 0.89% for carbon-based products. The active sites of the catalysts are derived from the nitrogen atoms of unique triazine ring structure in the ordered porous framework and the abundant Cu-N coordination sites with bipyridine units. Furthermore, through DFT calculations and operando FTIR spectra analysis, we proposed a comprehensive mechanism for the photoelectrocatalytic CO₂ reduction, confirming the existence of key intermediate species such as *CO₂^-, *=C=O, *CHO and *CO-CHO etc. This work not only provides a new way to mimic photosynthesis of plant leaves but also gives a new opportunity to enter this research field in the future.