Semimetallic Bismuthene with Edge‐Rich Dangling Bonds: Broad‐Spectrum‐Driven and Edge‐Confined Electron Enhancement Boosting CO₂ Hydrogenation Reduction

Broad-spectrum-driven high-performance artificial photosynthesis is quite challenging. Herein, atomically ultrathin bismuthene with semimetallic properties is designed and demonstrated for broad-spectrum (ultraviolet-visible-near infrared light) (UV-vis-NIR)-driven photocatalytic CO₂ hydrogenation. The trap states in the bandgap produced by edge dangling bonds prolong the lifetime of the photogenerated electrons from 90 ps in bulk Bi to 1650 ps in bismuthine, and excited-state electrons are enriched at the edge of bismuthine. The edge dangling bonds of bismuthene as the active sites for adsorption/activation of CO₂ increase the hybridization ability of the Bi 6p orbital and O 2p orbital to significantly reduce the catalytic reaction energy barrier and promote the formation of C─H bonds until the generation of CH₄. Under λ ≥ 400 nm and λ ≥ 550 nm irradiation, the utilization ratios of photogenerated electron reduction CO₂ hydrogenation to CO and CH₄ for bismuthene are 58.24 and 300.50 times higher than those of bulk Bi, respectively. Moreover, bismuthene can extend the CO₂ hydrogenation reaction to the near-infrared region (λ ≥ 700 nm). This pioneering work employs the single semimetal element as an artificial photosynthetic catalyst to produce a broad spectral response.