One-Pot Synthesis of 2D-2D WO3 /g-C3 N4 Photocatalyst in Reverse Microemulsion System via Supercritical CO2 for Enhanced Hydrogen Generation.

Construction of Z-scheme photocatalyst is an effective approach for using solar energy to produce hydrogen during water splitting. Herein, 2D/2D WO3 /g-C3 N4 heterojunction photocatalyst was synthesized by a convenient and green method including exfoliation and heterojunction procedures, in the reverse microemulsion system via supercritical carbon dioxide (scCO2 ). The resultant W/CN-10.3 composite exhibited enhanced photocatalytic activities towards the hydrogen evolution during water splitting with a hydrogen evolution rate of 688.51 µmol g-1 h-1 , which was more than 16 times higher than bulk g-C3 N4 with the same loading amount of Pt as cocatalyst. Due to its effective separation of photogenerated carriers and prolonged lifetime, more photoexcited electrons with high reduction ability could contribute to the production of H2 . Possible formation mechanism of 2D-2D WO3 /g-C3 N4 nanosheets via scCO2 in the reverse microemulsion system by the one-pot method has been proposed. This work provides an efficient and green strategy to synthesize 2D-2D heterojunction for the utilization in solar-to-fuel conversion.

A Facile Route to Synthesis of Hierarchically Porous Carbon via Micelle System for Bifunctional Electrochemical Application.

Well-ordered hierarchically porous carbon (HPC) nanomaterials have been successfully synthesized by a facile, efficient, and fast heated-evaporation induced self-assembly (HISA) method. A micelle system was employed as the template by using the HISA method for the first time, which possessed great potential in the large-scale production of HPC materials. Various surfactants, including triblock copolymer Pluronic F127, P123, F108, and cationic CTAB, were used in the polymerization process as templates to reveal the relationship between the structure of surfactants and architecture of the as-prepared HPCs. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Nitrogen adsorption, and Fourier transform infrared (FTIR) measurements were conducted to investigate the morphology, structure, and components of HPCs, which further confirmed the well-ordered and uniform mesoporous structure. The as-prepared HPC sample with F127 possessed the largest specific surface area, suitable pore size, and well-ordered mesoporous structure, resulting in better electrochemical performance as electrodes in the fields of energy storage and conversion system. Doped with the metallic oxide MnO2, the MnO2/HPC composites presented the outstanding electrochemical activity in supercapacitor with a high specific capacitance of 531.2 F g-1 at 1 A g-1 and excellent cycling performance with little capacity fading, even after 5,000 cycles. Moreover, the obtained sample could also be applied in the fields of oxygen reduction reaction (ORR) for its abundant active sites and regulate architecture. This versatile approach makes the mass industrial production of HPC materials possible in electrochemical applications through a facile and fast route.

Synthesis of Atomically Thin g-C3N4 Nanosheets via Supercritical CO2 Doping with Single-Atom Cobalt for Photocatalytic Hydrogen Evolution.

The atomically thin nanosheets of graphitic carbon nitride (g-C3N4) with mesopores have been successfully exfoliated with supercritical CO2 (scCO2). The thickness of the as-synthesized samples could be directly tailored by simply regulating the scCO2 pressure. The obtained bilayer mesoporous g-C3N4 nanosheets doped with monatomic Co through a microwave-assisted approach havve been employed as single-atom catalysts to enhance the photocatalytic hydrogen evolution performance. The as-prepared Co/P/CN-sc sample exhibited a boosted H2 production performance due to its unique structural advantages by exposing more active sites and facilitating the separation of charge carriers. Based on X-ray photoelectron spectroscopy, steady-state and time-resolved photoluminescence spectroscopy, X-ray absorption fine structure measurement, and density functional theory (DFT) calculations, a possible mechanism has been proposed. The work shows a new perspective for designing an inexpensive photocatalyst with a unique structure through a facile and green approach for photocatalytic hydrogen evolution.