Polypyrrole-Promoted rGO–MoS2 Nanocomposites for Enhanced Photocatalytic Conversion of CO2 and H2O to CO, CH4, and H2 Products

Advanced functionalized nanomaterials are indispensable for the efficient production of solar fuels via the reduction of CO2 under solar light. This approach simultaneously addresses two major issues: (a) global warming due to anthropogenic CO2 production and (b) the ongoing energy crisis. Owing to their high catalytic activity and visible-light absorption, MoS2 has recently emerged as a suitable candidate for the photocatalytic production of solar fuels from water splitting and CO2 reduction. However, it currently shows poor conversion efficiency because of low adsorption of reactant gases, fast radiative recombination, and low chemical stability; these factors limit their practical applicability. In this work, CO2 photoreduction and H2 production were enhanced by integrating photoabsorber MoS2 and N-containing conducting polymer polypyrrole (PPy) on reduced graphene oxide (rGO). rGO–MoS2/PPy nanocomposites with various amounts of PPy were fabricated and morphologically, structurally, and optically characterized using several techniques. The optimal rGO–MoS2/PPy nanocomposite was found to exhibit a remarkable production of CO (3.95 μmol g–1 h–1), CH4 (1.50 μmol g–1 h–1), and H2 (4.19 μmol g–1 h–1) in the photocatalytic reduction of CO2 in an aqueous suspension under simulated sunlight. The enhanced photocatalytic performance of the nanocomposites was attributed to the beneficial combination of the rGO skeleton, MoS2 nanosheets, and in situ polymerized conductive PPy; this effectively promoted charge transfer, delayed recombination, improved light absorption, and CO2 adsorption. In summary, this study describes an inexpensive non-noble metal photocatalyst with three components for the efficient photoreduction of CO2 into clean solar fuels.