Tailoring the properties of oxygenated graphene with different oxidation degrees for noble-metal-free photocatalytic hydrogen evolution

摘要

This present work demonstrates the integration of oxygen atoms into the graphene matrix to develop graphene oxide (GO) with tailored oxidation degrees which render them as photoactive materials for hydrogen (H-2) evolution. GO photocatalysts derived from the modified Hummer's method can endow tunable optical and electronic properties by varying the oxidation level into three increasing degrees GO-0.33, GO-0.47 and GO-0.53. Absorption spectroscopy revealed the increasing band gap of GO with respect to increasing oxygen contents and XRD, Raman and AFM studies revealed transformation in properties with increasing degree of oxygenated graphene. As opposed to graphite or graphene which is not photoresponsive, all GO samples exhibited photocatalytic activity towards H-2 generation in sacrificial systems containing 0.1 M Na2S/Na2SO3. Among the studied samples, GO with intermediate O/C ratio of 0.47 (GO-0.47) exhibited the highest H-2 photoactivity of 1104.3 mu molg(-1)h(-1) after of light irradiation, owing to the presence of optimal oxygen loading content in GO. The study reveals that mere chemical modification by oxygen groups on the graphene can confer photocatalytic properties whose activity is further adjustable by modification in the oxygen level.