ABSTRACT
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 CâH 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.
ABSTRACT
According to the typical Sillén-structured BiOBr, a simple solvothermal method was used to successfully synthesise Sillén-structured bimetallic oxyhalide CdBiO2Br with the existence of 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br), a kind of reactive ionic liquid. The introduction of the metal cadmium, which can form Sillén-structured bimetallic oxyhalide, made the alternating structure of BiOBr originally [Bi2O2]2+ and bilayer Br- modified to that of [CdBiO2]+ and monolayer Br-. So that the distance between layer and layer is greatly shortened, which facilitates the migration and separation of photogenerated carriers and promotes the generation of more reactive oxygen species. After modification, the band positions of CdBiO2Br materials can make more full use of visible light and more favourable utilisation of solar resources. As confirmed by radical trapping analysis and ESR analysis, superoxide radical (·O2-) and hole (h+) acted the major part during photocatalysis. The possible intermediate products that appeared during the degradation progress were analyzed by LC-MS. Moreover, the generation of superoxide ions was quantitatively analyzed by nitroblue tetrazolium chloride (NBT). In this paper, we present an ultra-thin layered material for visible light catalysis, which enlightens a feasible scheme for the research and development of new layered photocatalytic materials.
