Vertically Aligned Oxygenated-CoS₂–MoS₂ Heteronanosheet Architecture from Polyoxometalate for Efficient and Stable Overall Water Splitting

To achieve efficient conversion of renewable energy sources through water splitting, low-cost, earth-abundant, and robust electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required. Herein, vertically aligned oxygenated-CoS₂–MoS₂ (O-CoMoS) heteronanosheets grown on flexible carbon fiber cloth as bifunctional electrocatalysts have been produced by use of the Anderson-type (NH₄)₄[Co^IIMo₆O₂₄H₆]·6H₂O polyoxometalate as bimetal precursor. In comparison to different O-FeMoS, O-NiMoS, and MoS₂ nanosheet arrays, the O-CoMoS heteronanosheet array exhibited low overpotentials of 97 and 272 mV to reach a current density of 10 mA cm^–2 in alkaline solution for the HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, O-CoMoS heteronanosheets as both the anode and cathode deliver a current density of 10 mA cm^–2 at a quite low cell voltage of 1.6 V. This O-CoMoS architecture is highly advantageous for a disordered structure, exposure of active heterointerfaces, a “highway” of charge transport on two-dimensional conductive channels, and abundant active catalytic sites from the synergistic effect of the heterostructures, accomplishing a dramatically enhanced performance for the OER, HER, and overall water splitting. This work represents a feasible strategy to explore efficient and stable bifunctional bimetal sulfide electrocatalysts for renewable energy applications

Vertically Aligned Oxygenated-CoS₂–MoS₂ Heteronanosheet Architecture from Polyoxometalate for Efficient and Stable Overall Water Splitting

To achieve efficient conversion of renewable energy sources through water splitting, low-cost, earth-abundant, and robust electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are required. Herein, vertically aligned oxygenated-CoS₂–MoS₂ (O-CoMoS) heteronanosheets grown on flexible carbon fiber cloth as bifunctional electrocatalysts have been produced by use of the Anderson-type (NH₄)₄[Co^IIMo₆O₂₄H₆]·6H₂O polyoxometalate as bimetal precursor. In comparison to different O-FeMoS, O-NiMoS, and MoS₂ nanosheet arrays, the O-CoMoS heteronanosheet array exhibited low overpotentials of 97 and 272 mV to reach a current density of 10 mA cm^–2 in alkaline solution for the HER and OER, respectively. Assembled as an electrolyzer for overall water splitting, O-CoMoS heteronanosheets as both the anode and cathode deliver a current density of 10 mA cm^–2 at a quite low cell voltage of 1.6 V. This O-CoMoS architecture is highly advantageous for a disordered structure, exposure of active heterointerfaces, a “highway” of charge transport on two-dimensional conductive channels, and abundant active catalytic sites from the synergistic effect of the heterostructures, accomplishing a dramatically enhanced performance for the OER, HER, and overall water splitting. This work represents a feasible strategy to explore efficient and stable bifunctional bimetal sulfide electrocatalysts for renewable energy applications

BiVO₄‑Based Heterojunction Photocathode for High-Performance Photoelectrochemical Hydrogen Peroxide Production

Photoelectrochemical (PEC) cells provide a promising solution for the synthesis of hydrogen peroxide (H2O2). Herein, an integrated photocathode of p-type BiVO4 (p-BVO) array with tetragonal zircon structure coupled with different metal oxide (MOx, M = Sn, Ti, Ni, and Zn) heterostructure and NiNC cocatalyst (p-BVO/MOx/NiNC) was synthesized for the PEC oxygen reduction reaction (ORR) in production of H2O2. The p-BVO/SnO2/NiNC array achieves the production rate 65.46 μmol L–1 h–1 of H2O2 with a Faraday efficiency (FE) of 76.12%. Combined with the H2O2 generation of water oxidation from the n-type Mo-doped BiVO4 (n-Mo:BVO) photoanode, the unbiased photoelectrochemical cell composed of a p-BVO/SnO2/NiNC photocathode and n-Mo:BVO photoanode achieves a total FE of 97.67% for H2O2 generation. The large area BiVO4-based tandem cell of 3 × 3 cm2 can reach a total H2O2 production yield of 338.84 μmol L–1. This work paves the way for the rational design and fabrication of artificial photosynthetic cells for the production of liquid solar fuel