Integration of Nitrogen-Doped Amorphous Carbon with TiO 2 Nanoparticles for Modulating Photocatalytic Reduction of CO 2 to Methane

Poor adsorption and sulfate-induced high carrier recombination limit the CO 2 photocatalytic reduction activity of TiO 2 nanoparticles (anatase phase, average diameter ∼15 nm, and specific surface area 37.42 m 2 /g), as well as the generation of C–H added-value compounds. In this work, the difficulty of generating CH 4 by photoreduction of CO 2 on TiO 2 was solved by constructing a composite of porous nitrogen-doped activated carbon (p-CN-2) with hierarchical nanochannels (5–20 nm), nanopores (<5 nm), and TiO 2 nanoparticles. The introduction of p-CN-2 promoted the adsorption of CO 2 and proton generation. Meanwhile, pyridine N in p-CN-2 interacts with TiO 2 to establish a Ti–N–C photocarrier separation channel to enhance the effective photogenerated charge density. Promoted CO 2, protons, and photocarrier concentrations modulate the occurrence of photocatalytic CO 2 methanation on TiO 2 . The CH 4 4 h yield of TiO 2 /p-CN-2 is 47.12 μmol·g –1, which is about 50 times higher than that of TiO 2 . The CH 4 selectivity of TiO 2 /p-CN-2 increases from 15.53% TiO 2 to 82.05%. This work presents a facile and effective method for facilitating photocatalytic CO 2 methanation using TiO 2 as a model. This work presents a facile and effective method for facilitating photocatalytic CO 2 methanation using TiO 2 nanoparticles as a model, and the prepared TiO 2 /p-CN-2 nanocomposite is particularly well-suited for solar-driven CO 2 methanation in carbon recycling systems and renewable energy production (e.g., coupling with photovoltaic devices for green CH 4 fuel synthesis).