Trace Cu+-dominated band structure engineering in CuxIn0.25ZnSy for promoting photocatalytic H2 evolution

Bifunctional In3+ Doping toward Defect Engineering in SrTiO3 for Solar Water Splitting

Defect engineering in SrTiO3 crystals plays a pivotal role in achieving efficient overall solar water splitting, as evidenced by the influence of Al3+ ions. However, the uneven structural relaxation caused by Al3+ ions has been overlooked, significantly affecting the defect state and catalytic activity. When an Al2O3 crucible is used, optimizing this defect engineering presents a significant challenge. In this study, we introduced In3+ into the SrTiO3 crystal to achieve favorable photocatalytic performance. Notably, In3+ stabilizes at the B sites of SrTiO3, outcompeting Al3+, demonstrating a bifunctional effect by simultaneously regulating the concentration of defect charges and mitigating the negative impact of Al3+ on structural relaxation, leading to shallow-state defects. Additionally, the incorporation of In3+ ions effectively prevents the precipitation of perovskite Sr2+. Carrier behavior studies and density functional theory (DFT) calculations provide substantial evidence of the underlying modulating mechanism. Consequently, the optimized In3+-doped SrTiO3 exhibits impressive gas evolution rates of 1.40 mmol·h-1 H2 and 0.69 mmol·h-1 O2 under full-spectrum light irradiation, corresponding to a promising apparent quantum yield (AQY) of 82.36% at 365 nm and a solar-to-hydrogen (STH) efficiency of 0.54%. Such enhanced activity could be attributed to the effective incorporation of In3+ ions, which improves the structural stability of the perovskite SrTiO3 lattice.

Quasi-type-II Cu-In-Zn-S/Ni-MOF heterostructure with prolonged carrier lifetime for photocatalytic hydrogen production

Visible-driven photocatalytic hydrogen production using narrow-bandgap semiconductors has great potential for clean energy development. However, the widespread use of these semiconductors is limited due to problems such as severe charge recombination and slow surface reactions. Herein, a quasi-type-II heterostructure was constructed by combining bifunctional Ni-based metal-organic framework (Ni-MOF) nanosheets with BDC (1,4-benzenedicarboxylic acid) linker coupled with Cu-In-Zn-S quantum dots (CIZS QDs). This heterostructure exhibited a prolonged charge carrier lifetime and abundant active sites, leading to significantly improved hydrogen production rate. The optimized rate achieved by the CIZS/Ni-MOF heterostructure was 2642 μmol g-1 h-1, which is 5.28 times higher than that of the CIZS QDs. This improved performance can be attributed to the quasi-type-II band alignment between the CIZS QDs and Ni-MOF, which facilitates effective delocalization of the photogenerated electrons within the system. Additional photoelectrochemical tests confirmed the well-maintained photoluminescence and prolonged charge carrier lifetime of the CIZS/Ni-MOF heterostructure. This study provides valuable insights into the use of multifunctional MOFs in the development of highly efficient composite photocatalysts, extending beyond their role in light harvesting and charge separation.

Matrix-type bismuth-modulated copper-sulfur electrode using local photothermal effect strategy for efficient seawater splitting

Constructing catalytic electrodes with green economy, stability, and high efficiency is crucial for achieving overall economic water splitting. Herein, a matrix-type bismuth-modulated nickel-boron electrodes loaded on sulfurized copper foils (Bi-NiBx@CFS) is synthesized via in situ mild electroless plating. This electrode features a 2-dimensional (2D) matrix-type nanosheet structure with uniform, large pores, providing more active sites and ensuring a high gas transmission rate. Notably, the crystalline-amorphous structure constituted by the photothermal materials Bi and NiBx is loaded onto sulfide-based heterostructures. This enhances the catalytic activity through the "local photothermal effect" strategy. A performance enhancement of approximately 10 % is achieved for the Bi-NiBx@CFS at a current density of 10 mA cm-2 using this strategy at 298 K. This enhancement is equivalent to increasing the temperature of conventional electrolyte solutions by 321 K. In addition, the overpotential required to catalytically drive seawater splitting at the same current density is only 1.486 V. The Bi-NiBx@CFS electrode operates stably for 200 h without any performance degradation at industrial-grade current densities. The Bi-NiBx@CFS electrode under the "localized photothermal effect" strategy is expected to be a new type of electrocatalyst for overall seawater splitting.

Integrated Coupling Utilization of the Solar Full Spectrum for Promoting Water Splitting Activity over a CIZS Semiconductor

Most of the existing photocatalysts can only use ultraviolet light and part of visible light, so broadening the spectrum response range and realizing the full spectrum coverage are key measures to improve the solar-to-hydrogen (STH) efficiency of photocatalytic water splitting. A spatially separated photothermal coupled photocatalytic (PTC) reaction system was designed using carbonized melamine foam (C-MF) as a substrate to absorb visible and infrared light and Cu_0.04In_0.25ZnS_y@Ru (CIZS@Ru) as a photocatalyst to absorb UV-visible light (UV-vis). By comparing the three modes of bottom, liquid level, and self-floating, it is found that the surface temperature of the system has a significant effect on the hydrogen evolution activity. The monochromatic light and activation energy experiments verify that the enhancement of photocatalytic activity comes from the strengthened photothermal effect of the substrate. Combined with theoretical calculations, it is further confirmed that the introduction of photothermal materials provides additional kinetic energy for carrier transmission and promotes directional carrier transmission efficiency. Based on the photoenergy-thermal integrated catalytic strategy, the hydrogen production rate reaches 603 mmol h^-1 m^-2. The structural design of photocatalysis has potential application in the field of photoenergy-fuel conversion.