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.