Yijia Wei

Monoclinic Porous BiVO4 Networks Decorated by Discrete g-C3N4 Nano-Islands with Tunable Coverage for Highly Efficient Photocatalysis

An efficient g-C3N4/BiVO4 heterojunction photocatalyst is constructed with BiVO4 networks decorated by discrete g-C3N4 nano-islands with controllable coverage. The as-synthesized g-C3N4/BiVO4 photo-catalyst shows superior visible light photocatalytic activity. The enhanced photocatalytic activity can be ascribed to increased charge separation efficiency, separated redox reaction sites, fully exposed reactive interfaces, and excellent visible light response of g-C3N4/BiVO4 composite.

Stable Aqueous Photoelectrochemical CO2 Reduction by a Cu2O Dark Cathode with Improved Selectivity for Carbonaceous Products

Photocatalytic reduction of CO2 to produce fuels is a promising way to reduce CO2 emission and address the energy crisis. However, the H2 evolution reaction competes with CO2 photoreduction, which would lower the overall selectivity for carbonaceous products. Cu2 O has emerged as a promising material for suppressing the H2 evolution. However, it suffers from poor stability, which is commonly regarded as the result of the electron-induced reduction of Cu2 O. This paper describes a simple strategy using Cu2 O as a dark cathode and TiO2 as a photoanode to achieve stable aqueous CO2 reduction with a high Faradaic efficiency of 87.4 % and a selectivity of 92.6 % for carbonaceous products. We have shown that the photogenerated holes, instead of the electrons, primarily account for the instability of Cu2 O. Therefore, Cu2 O was used as a dark cathode to minimize the adverse effects of holes, by which an improved stability was achieved compared to the Cu2 O photocathode under illumination. Additionally, direct exposure of the Cu2 O surface to the electrolyte was identified as a critical factor for the high selectivity for carbonaceous products.

Thin Heterojunctions and Spatially Separated Cocatalysts To Simultaneously Reduce Bulk and Surface Recombination in Photocatalysts

Efficient charge separation and light absorption are crucial for solar energy conversion over solid photocatalysts. This paper describes the construction of Pt@TiO2 @In2 O3 @MnOx mesoporous hollow spheres (PTIM-MSs) for highly efficient photocatalytic oxidation. TiO2 -In2 O3 double-layered shells were selectively decorated with Pt nanoparticles and MnOx on the inner and outer surfaces, respectively. The spatially separated cocatalysts drive electrons and holes near the surface to flow in opposite directions, while the thin heterogeneous shell separates the charges generated in the bulk phase. The synergy between the thin heterojunctions and the spatially separated cocatalysts can simultaneously reduce bulk and surface/subsurface recombination. In2 O3 also serves as a sensitizer to enhance light absorption. The PTIM-MSs exhibit high photocatalytic activity for both water and alcohol oxidation.

A Low-Cost NiO Hole Transfer Layer for Ohmic Back Contact to Cu2O for Photoelectrochemical Water Splitting

Cuprous oxide (Cu2 O) photocathode is reported as a promising candidate for photoelectrochemical water splitting. The p-type Cu2 O usually forms a Schottky junction with the conductive substrate due to its large work function, which blocks the collection of photogenerated holes. NiO is considered as one of the most promising hole transfer layers (HTL) for its high hole mobility, good stability, and easy processability to form a film by spin coating. The utilization of NiO HTL to form an Ohmic back contact to Cu2 O is described, thus achieving a positive onset potential of 0.61 V versus reversible hydrogen electrode and a twofold increase of solar conversion efficiency.