Near-infrared absorbing 2D/3D ZnIn2S4/N-doped graphene photocatalyst for highly efficient CO2 capture and photocatalytic reduction

Hierarchical heterostructure photocatalysts with broad spectrum solar light utilization, particularly in the near-infrared (NIR) region, are emerging classes of advanced photocatalytic materials for solar-driven CO2 conversion into value-added chemical feedstocks. Herein, a novel two-demensional/three-demensional (2D/3D) hierarchical composite is hydrothermally synthesized by assembling vertically-aligned ZnIn2S4 (ZIS) nanowall arrays on nitrogen-doped graphene foams (NGF). The prepared ZIS/NGF composite shows enhancement in photothermal conversion ability and selective CO2 capture as well as solar-driven CO2 photoreduction. At 273 K and 1 atm, the ZIS/NGF composite with 1.0 wt% NGF achieves a comparably high CO2-to-N-2 selectivity of 30.1, with an isosteric heat of CO2 adsorption of 48.2 kJ mol(-1). And in the absence of cocatalysts and sacrificial agents, the ZIS/NGF composite with cyclability converts CO2 into CH4, CO and CH3OH under simulated solar light illumination, with the respective evolution rates about 9.1, 3.5, and 5.9 times higher than that of the pristine ZIS. In-depth analysis using in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) in conjunction with Kelvin probe measurements reveals the underlying charge transfer pathway and process from ZIS to NGF.