Nowdays, the nonprecious, non-metallic carbon-based electrocatalysts are perceived to receive more attention due to its excellent electrical conductivity, tunable molecular structures, abundance, and strong tolerance to acidic/alkaline environments properties. Explicitly, the graphitic carbon nitride (g-C3N4) materials are in virtuous progress and well-thought-out to be a promising catalyst for photoelectrochemical (PEC) water splitting system due to visible-light driven band gap and proper band edges. However, the intrinsical fast recombination rate of the photo-induced charge carriers of g-C3N4 seems to be a crucial barrier to generate an efficient catalytic activity. To overcome this decisive disadvantage, the enrichment of heterojunction with g-C3N4 and reduced graphene oxide (rGO) was anticipated to enhance the electrochemical catalytic activity. Generally, the formation of heterojunctions results in the efficient separation of electron-hole pairs to minimize the energy-wasteful electron-hole recombination, which leads to the high PEC catalytic activity. Herein, we tailored the heterojunction PEC catalysts between rGO and g-C3N4, that both of these catalysts exhibit effective toward water splitting. Incidentally, two kinds of rGOs were prepared, one acts as the pristine rGO, and the other one is the defective rGO through air plasma treatment. According to the DFT calculations, the effect of the existence of defects in the rGO facilitates to eliminate the proven band gap. Hence, the prepared pristine rGO was employed as photocatalyst which shows specific band gap and the defective rGO was engaged as an electrochemical catalyst which has no band gap with respect to the obtained theoretical results. Besides, to boosting the photocatalytic effect, the C3N4 was also used in this system with the corresponding loading amount of ratio of pristine rGO: defective rGO: g-C3N4 = 3:2:5. As the results, the sample consisting the heterojunction between pristine rGO, defective rGO and g-C3N4 were perceived to exhibit an improved efficiency towards water splitting than those of the rGO and g-C3N4 catalysts. Regarding the hydrogen evolution reaction (HER) activity, the current density at -0.6 V (vs. RHE) under light illumination shows 1.85 times higher than in the dark, which result has same tendency with the OER activity. In summary, we have tailored a novel nonprecious carbon-based catalyst with heterojunction that works efficiently on full water splitting reaction.

Heterojunction of reduced graphene oxide and graphitic-carbon nitride as a bi-functional photoelectrochemical catalyst for water splitting reaction

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.