Wittichenite semiconductor of Cu3BiS3 films for efficient hydrogen evolution from solar driven photoelectrochemical water splitting.

A highly efficient, low-cost and environmentally friendly photocathode with long-term stability is the goal of practical solar hydrogen evolution applications. Here, we found that the Cu3BiS3 film-based photocathode meets the abovementioned requirements. The Cu3BiS3-based photocathode presents a remarkable onset potential over 0.9 VRHE with excellent photoelectrochemical current densities (~7 mA/cm2 under 0 VRHE) and appreciable 10-hour long-term stability in neutral water solutions. This high onset potential of the Cu3BiS3-based photocathode directly results in a good unbiased operating photocurrent of ~1.6 mA/cm2 assisted by the BiVO4 photoanode. A tandem device of Cu3BiS3-BiVO4 with an unbiased solar-to-hydrogen conversion efficiency of 2.04% is presented. This tandem device also presents high stability over 20 hours. Ultimately, a 5 × 5 cm2 large Cu3BiS3-BiVO4 tandem device module is fabricated for standalone overall solar water splitting with a long-term stability of 60 hours.

Rapid thermal deposited GeSe nanowires as a promising anode material for lithium-ion and sodium-ion batteries.

It is important to develop a simple, facile and environmentally friendly strategy for improving the properties of materials in various energy storage systems. Herein, a binder-free anode based on self-assembled nanowires structures with GeSe particles is formed through a rapid box thermal deposition and first reported as an advanced anode for lithium/sodium-ion batteries. For LIBs, it delivers an excellent energy storage performance with high specific capacity (~815.49 mAh g-1 at 200 mA g-1 after 300 cycles), superior rate capability (~578.49 mAh g-1 for 10 cycles at 4000 mA g-1) and outstanding cycling stability (~87.78% of capacity retention after 300 cycles). It even shows a high reversible capacity of 359.5 mAh g-1 at 500 mA g-1 after 2000 cycles. For SIBs, it shows good cycling stability (~433.4 mAh g-1 at 200 mA g-1 after 50 cycles with ~85.3% capacity retention) and rate performance (~299.7 mAh g-1 for 10 cycles at 1000 mA g-1). In this electrode, GeSe nanowires (GeSe-NWs) consist of nanoparticles with voids between them that shorten the diffusion length for lithium/sodium ions and electrons and buffer the volumetric variation during the lithium/sodium ion insertion/extraction process. In addition, the introduction of Ni foam frameworks enhances the electrical conductivity of the electrode and retains the structural integrity upon cycling. This approach provides a new perspective for investigating and synthesizing various novel and suitable materials for energy storage fields.

Environmentally friendly Cu2ZnSnS4-based photocathode modified with a ZnS protection layer for efficient solar water splitting.

High-quality Cu2ZnSnS4 (CZTS) thin films prepared by spray pyrolysis on a Mo-coated glass substrate were used for solar water splitting in this study. Modification of a CdS layer under CZTS improved the photocatalysis efficiency by forming a pn junction between CdS and CZTS, effectively separating the photoexcited carriers without recombination. However, the photocorrosive nature of CdS induces poor stability of the CdS/CZTS photocathode. Surface protection of a CdS-covered CZTS photocathode by a ZnS layer resulted in efficient photoelectrochemical water splitting with a maximum half-cell solar to hydrogen (HC-STH) efficiency of 2.1% and without showing appreciable degradation. The ZnS layer acts as a mediator for efficient electron transport to Pt deposits and as a protective layer, preventing contact between the CdS layer and the outer electrolyte solution.