Effect of nonmetals (B, O, P, and S) doped with porous g-CN for improved electron transfer towards photocatalytic CO reduction with water into CH.

Photocatalytic conversion of carbon dioxide (CO) into gaseous hydrocarbon fuels is an auspicious way to produce renewable fuels in addition to greenhouse gas emission mitigation. In this work, non-metals (B, O, P, and S) doped graphitic carbon nitride (g-CN) was prepared via solid-state polycondensation of urea for photocatalytic CO reduction into highly needed methane (CH) with water under UV light irradiation. The various physicochemical characterization results reveal the successful incorporation of B, O, P, and S elements in the g-CN matrix. The maximum CH yield of 55.10 nmol/(mL.g) over S-doped g-CN has been obtained for CO reduction after 7 h of irradiation. This amount of CH production was 1.9, 1.4, 1.7, and 2.4-folds higher than B, O, P and bare g-CN samples. The doping of S did not enlarge the surface area and photon absorption ability of the g-CN sample, but this significant improvement was evidently due to effective charge separation and migration. The observed results imply that the doping of non-metal elements provides improved charge separation and is an effective way to boost photocatalyst performance. This work offers an auspicious approach to design non-metal doped g-CN photocatalysts for renewable fuel production and would be promising for other energy application.