The development of an advanced cocatalyst is critical for improving the efficiency of the photocatalytic hydrogen evolution reaction. Noble metals such as platinum (Pt) have been identified to be the most active cocatalyst for this reaction; however, due to their low-abundance, high cost, their usage in the scale-up setup is impeditive. Here, we report a high active cocatalyst, limited-layered MoS2 confined on RGO sheets as an alternative of Pt, for hydrogen evolution in dye-sensitized photocatalytic systems. Growing a MoS2 cocatalyst on RGO sheets provides more available catalytically edge sites and thus exhibits much higher activity than large aggregated pristine MoS2 particles under visible light irradiation (≥420 nm). The apparent quantum efficiency (AQE) of 24% at 460 nm over an Eosin Y-sensitized MoS2/RGO photocatalyst has been achieved. In addition, the electrical coupling and synergistic effect between MoS2 and RGO sheets greatly facilitate the efficient electron transfer from photoexcited dye to the active edge sites of MoS2; as a result, the prolonged lifetime of photogenerated electrons and the improved charge separation efficiency have been accomplished, and the photocatalytic hydrogen evolution activity has been enhanced significantly. This work demonstrates that the structural integration of MoS2 with RGO will be a new promising strategy to develop a high efficient and low-cost non-noble metal cocatalyst for solar hydrogen generation.

Graphite oxide was prepared from natural graphite using a modified Hummers method. Briefly, graphite powder (100 g) was added to an 80 ℃ mixture solution of concentrated H 2 SO 4 (150 mL), K 2 S 2 O 8 (50 g), and P 2 O 5 (50 g). The resultant mixture was isolated and allowed to cool down to room temperature. Then the mixture was diluted with distill water (7.5 L) and the product was filtered, washed with distilled water until the filtrate pH become neutral. The product was dried in air at room temperature for 24 h. Subsequently, the preoxidized graphite (20 g) and NaNO 3 (10 g) were added to cold concentrated H 2 SO 4 (0 ℃, 460 mL). KMnO 4 (60 g) was then added gradually with stirring and cooling so that the temperature of the mixture was kept below 20 ℃. The mixture was then stirred at 35 ℃ for 2 h. Distilled water (920 mL) was slowly added to the mixture, followed by stirring for 15 min.The reaction was terminated by adding distilled water (2.8 L) and then H 2 O 2 solution (50 mL, 30%).The product was filtered, washed repeatedly with HCl (1:10, v/v) until sulfate could not be detected with BaCl 2 , and then dried in a vacuum oven at 40 ℃ for 24 h.

Herein we introduce a straightforward, low cost, scalable, and technologically relevant method to manufacture an all-carbon, electroactive, nitrogen-doped nanoporous-carbon/carbon-nanotube composite membrane, dubbed "HNCM/CNT". The membrane is demonstrated to function as a binder-free, high-performance gas diffusion electrode for the electrocatalytic reduction of CO to formate. The Faradaic efficiency (FE) for the production of formate is 81 %. Furthermore, the robust structural and electrochemical properties of the membrane endow it with excellent long-term stability.