Construction of 2D/2D Bi2Se3/g-C3N4 nanocomposite with High interfacial charge separation and photo-heat conversion efficiency for selective photocatalytic CO2 reduction

Solar-energy-driven CO2 conversion into high-valued fuels has been considered as a promising strategy to alleviate the greenhouse effect and energy crisis problems. However, the rapid charge recombination, poor light utilization and low selectivity, etc. still limit the efficiency of photocatalytic CO2 reduction. In this work, a novel 2D/2D Bi2Se3/g-C3N4 heterojunction composite has been developed to investigate the improved photocatalytic activity towards CO2 reduction selectively. Fortunately, an intimate interaction was formed between 2D Bi2Se3 and 2D g-C3N4, which is very beneficial for the charge separation and transfer. In this composite, Bi2Se3 not only acted as a cocatalyst liked role, but also played as an extra heater for photocatalytic reaction by effective photo-to-heat conversion. As expected, the 2D/2D Bi2Se3/g-C3N4 composite presented much improved photocatalytic ability for CO2 reduction to CO, which is about 6.3 times higher than that of pristine g-C3N4 under the irradiation of full spectrum. Notably, the product from CO2 reduction was nearly 100% CO without other carbon products, and the selectivity for CO was greater than 90% over H2 evolution. The experimental tests and DFT calculations confirmed that the superiority of photocatalytic CO2 reduction ability of Bi2Se3/g-C3N4 composite over other counterparts should be attributed to the synergetic effect of highly improved charge separation and strong photo-to-heat conversion efficiency. Meanwhile, the CO2 reduction process was studied by in-situ FTIR in detail. The as-proposed composite in this work might provide a potential strategy for developing high efficiency of photocatalytic CO2 reduction to valuable fuels.