Manganese Cadmium Sulfide Nanoparticles Solid Solution on Cobalt Acid Nickel Nanoflakes: A Robust Photocatalyst for Hydrogen Evolution

Synergistic regulation of d-band center photocatalytic hydrogen evolution at S-scheme heterojunction reduction sites through defect engineering and interface electric field

The efficiency of photocatalytic hydrogen evolution can be significantly enhanced while maintaining cost-effectiveness through the synergistic effect of defect surface engineering and multi-component heterojunctions. The structure and properties of NiCo2O4 nanorods were modified by inducing oxygen vacancies at different temperatures in this study, resulting in improved optical properties and electron adsorption capacity. The presence of oxygen vacancies leads to a reduction in the band gap of NiCo2O4, thereby enhancing electron transport efficiency through band gap engineering. Simultaneously, surface properties undergo changes, and vacancy defects serve as electron trapping centers, facilitating an increased participation of electrons in the hydrogen evolution reaction process. The dodecahedron KMP with a cavity structure is additionally introduced to form an S-scheme heterojunction with NiCo2O4. This establishes a novel mechanism for electron transport, which effectively enhances the separation of electron-hole pairs and improves the redox capacity of the photocatalytic system. The adsorption of intermediates in the hydrogen production process is enhanced through synergistic regulation of d-band centers via surface defect engineering and S-scheme heterojunction. Additionally, this approach improves the separation efficiency of electron-hole pairs and accelerates electron transfer dynamics, significantly enhancing hydrogen production efficiency.

Synergistic optimization of triple phase junctions and oxygen vacancies over MnxCd1-xS/Ov-WO3 for boosting photocatalytic hydrogen evolution

Strengthening the separation of photogenerated charge carriers is crucial for improving the efficiency of photocatalytic hydrogen evolution. Herein, t-Mn0.5Cd0.5S/Ov-WO3 (t-MCSW) triple-phase junctions with rich oxygen vacancies were developed using the calcination-hydrothermal method. The corresponding morphology and structure of the samples were examined by XRD, TEM and XPS. The formation of the S-scheme heterostructure in t-MCSW has also been confirmed with in situ XPS, work function analysis and free radical capture tests. The experimental results demonstrate that t-MCSW-7 exhibited optimal activity (194.2 mmol g-1 h-1), which was about 4 times higher than that of the individual Mn0.5Cd0.5S (t-MCS, 48.8 mmol g-1 h-1). The apparent quantum yield of t-MCSW-7 is 29.14% at 420 nm, and the material exhibits excellent stability after seven cycles of photocatalytic reaction. The excellent photocatalytic activity of t-MCSW-7 is attributed to more efficient separation of charge carriers by triple-phase junctions connected by homojunctions and heterojunctions. Moreover, the existence of oxygen vacancies broadens absorption spectra and accelerates surface charge transfer. The synergistic effect of phase junctions and oxygen vacancies leads to an enhancement of hydrogen evolution activity. This work provides a new idea for preparing efficient photocatalysts.

0D/2D Co0.85Se/TiO2 p–n heterojunction for enhanced photocatalytic H2 evolution

The H2 rate of 15%-Co0.85Se/TiO2 is 2312.5 μmol g−1 h−1, which is 10.3 times and 10.8 times higher than TiO2 and Co0.85Se. The enhanced activity is attributed to the higher electrochemically active surface area and the formation of p–n heterostructure.