ZnS is among the superior photocatalysts for H2 evolution, whereas the wide bandgap restricts its performance to only UV region. Herein, defect engineering and phase junction architecture from a controllable phase transformation enable ZnS to achieve the conflicting visible-light-driven activities for H2 evolution. On the basis of first-principle density functional theory calculations, electron spin resonance and photoluminescence results, etc., it is initially proposed that the regulated sulfur vacancies in wurtzite phase of ZnS play the key role of photosensitization units for charge generation in visible light and active sites for effective electron utilization. The symbiotic sphalerite-wurtzite phase junctions that dominate the charge-transfer kinetics for photoexciton separation are the indispensable configuration in the present systems. Neither ZnS samples without phase junction nor those without enough sulfur vacancies conduct visible-light photocatalytic H2 evolution, while the one with optimized phase junctions and maximum sulfur vacancies shows considerable photocatalytic activity. This work will not only contribute to the realization of visible light photocatalysis for wide-bandgap semiconductors but also broaden the vision on the design of highly efficient transition metal sulfide photocatalysts.

Ultrathin two dimensional (2D) materials have triggered extensive interest for their exceptional properties and potential applications. Herein, atomic layer graphitic carbon nitride (g-C3N4) was obtained by a simple ultrasonic exfoliation approach, and cadmium sulfide (CdS) nanoparticles were successfully grown on these ultrathin g-C3N4 nanosheets (UCNNS) via a facile solvothermal method. The as-prepared UCNNS-CdS nanocomposite exhibits significantly enhanced photocatalytic activity for methyl orange (MO) degradation under visible light irradiation. The enhancement of the photocatalytic activity should be attributed to the well-matched band structure and intimate contact interfaces between the UCNNS and CdS, which lead to the effective transfer and separation of the photogenerated charge carriers. The mechanism for the photodegradation of MO by the composite was also investigated in this study. This study highlights the potential applications of atomic layer g-C3N4 based photocatalysts, and we hope our work may provide a new insight for the construction of photocatalysts with efficient visible light activity.

Polyaniline (PANI) hybrid defective ZnO nanoparticles were synthesized by a facile chemisorption method together with a cold plasma treatment (CPT) technique. The PANI was dispersed uniformly onto the defective ZnO surface, and an intimate contact on the interface was observed. The coated PANI could act cooperatively with deliberately introduced defects (oxygen vacancy and interstitial zinc) to achieve remarkably enhanced photocatalytic activity. Moreover, the monomolecular-layered PANI could effectively stabilize defects on the surface of ZnO, which is of significance for practical application. It is hoped that the present work may provide an efficient and applicable method to develop photocatalysts with excellent performance.

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