Core-shell structure of sulphur vacancies-CdS@CuS: Enhanced photocatalytic hydrogen generation activity based on photoinduced interfacial charge transfer

Anisotropically Epitaxial P-N Heterostructures Actuating Efficient Z-Scheme Photocatalytic Water Splitting

Crafting anisotropically epitaxial p-n heterostructures with Z-scheme charge transmission is a promising avenue toward excellent photocatalytic efficiency, yet the large lattice mismatch and diverse crystal growth habits between components have often arisen as a big challenge to this goal. Here, anisotropically epitaxial p-n heterostructures with 19.8% lattice mismatch are obtained via a dynamics-mediated seeded growth tactic under reaction temperature as low as 60 °C. Structural analyses reveal the epitaxy of hexagonal CuS nanoplates onto CdS nanowires through forming misfit dislocations at {101̄0} interface and stacking faults inside CuS nanoplates. Experimental and density functional theory calculation results verify the Z-scheme photo-carriers transfer in epitaxial CdS-CuS heterostructures, which exhibit a much enhanced visible-light-driven H2 generation capability than non-epitaxial CdS/CuS counterpart, and the site-specified NiOOH photo-deposition over CdS-CuS heterostructures leads to a distinguished H2-evolving activity ≈65 and 36 times promotion compared to those of pristine CdS and Pt-loaded (3 wt.%) CdS, respectively. The study can enlighten new thinking to the steerable synthesis of epitaxial nanostructures with large lattice mismatch for various promising applications.

Copper Sulfide based Photocatalysts, Electrocatalysts and Photoelectrocatalysts: Innovations in Structural Modulation and Application

Copper sulfides (CuxS, 1 ≤ x ≤ 2) are notable for their unique photoelectric properties and potential applications, particularly in photo/electrocatalysis. These materials are valued for their tunable band gap, near-infrared optical characteristics, and plasmonic resonance effects. However, challenges such as low catalytic activity and limited stability impede their practical applications. This review addresses these issues by exploring advanced strategies for electronic structure modulation, including atomic doping, shape alteration, heterojunction construction, and defect introduction to enhance catalytic efficiency. A detailed analysis of the optical and electrical properties of CuxS across various stoichiometric ratios and crystal structures is provided, offering a comprehensive overview of their applications in photocatalysis, electrocatalysis, and photo/electrocatalysis. Additionally, the review synthesizes current knowledge and highlights the potential of these strategies to optimize CuxS-based photo/electrocatalysts, proposing future research directions to bridge the gap between theoretical studies and practical applications. This work underscores the importance of CuxS in photo/electrocatalysis and aims to inspire further innovation and exploration in this field, emphasizing its significance in material science and engineering.

Vacancy Engineering in 2D Transition Metal Chalcogenide Photocatalyst: Structure Modulation, Function and Synergy Application

Transition metal chalcogenides (TMCs) are widely used in photocatalytic fields such as hydrogen evolution, nitrogen fixation, and pollutant degradation due to their suitable bandgaps, tunable electronic and optical properties, and strong reducing ability. The unique 2D malleability structure provides a pre-designed platform for customizable structures. The introduction of vacancy engineering makes up for the shortcomings of photocorrosion and limited light response and provides the greatest support for TMCs in terms of kinetics and thermodynamics in photocatalysis. This work reviews the effect of vacancy engineering on photocatalytic performance based on 2D semiconductor TMCs. The characteristics of vacancy introduction strategies are summarized, and the development of photocatalysis of vacancy engineering TMCs materials in energy conversion, degradation, and biological applications is reviewed. The contribution of vacancies in the optical range and charge transfer kinetics is also discussed from the perspective of structure manipulation. Vacancy engineering not only controls and optimizes the structure of the TMCs, but also improves the optical properties, charge transfer, and surface properties. The synergies between TMCs vacancy engineering and atomic doping, other vacancies, and heterojunction composite techniques are discussed in detail, followed by a summary of current trends and potential for expansion.

Sulfur vacancy-rich (α/β-CdS)/SiO2 photocatalysts for enhanced visible-light-driven photocatalytic degradation of rhodamine B

The development of highly efficient photocatalysts for visible-light-driven degradation of organic pollution is of great interest for wastewater purification. In this work, a sulfur vacancy-rich (α/β-CdS)/SiO2 (α: hexagonal & β: cubic) photocatalyst with a high catalytic activity was novelly synthesized on a nano-SiO2 carrier by the reaction of Cd2+ with a CS2 storage material (CS2SM) as sulfur source and crystalline modifiers. The dispersion of α/β-CdS on the nano-SiO2 carrier significantly enhanced the visible-light-driven catalytic activity of (α/β-CdS)/SiO2 photocatalyst, and 93.37 % rhodamine B (RhB) conversion was determined over 50 mg (α/β-CdS)/SiO2 photocatalyst for 30 mL 400 mg/L RhB solution at light intensity of 150 mW/cm2 and 298.15 K. After five cycle tests, the (α/β-CdS)/SiO2 photocatalyst still owned excellent visible-light-driven catalytic degradation stability (>90 %). The characterizations of morphology, functional groups, and photo-electrochemistry of (α/β-CdS)/SiO2 photocatalyst demonstrated that nano-SiO2 as a carrier played meaningful role in dispersing α/β-CdS and reducing agglomeration, thus increasing the active site of photocatalytic degradation reaction, and the presence of α/β hetero-phase junctions and sulfur vacancies allows the rapid separation of photo-generated carriers and inhibits photo-generated electron-holes recombination. Meanwhile, the electron paramagnetic resonance (EPR) and free radical masking test have also proved that the main active species is ·O2- for the oxidation of RhB. Therefore, the work is providing a new reference to the visible-light-driven degradation of wastewater with high RhB concentration at room temperature.

Enhanced Photothermal Effect Assisted by Resonance Energy Transfer in Carbon/Covellite Core-Shell Nanoparticles toward a High-Performance Interfacial Water Evaporation Process

Carbon and semiconductor nanoparticles are promising photothermal materials for various solar-driven applications. Inevitable recombination of photoinduced charge carriers in a single constituent, however, hinders the realization of a greater photothermal effect. Core-shell heterostructures utilizing the donor-acceptor pair concept with high-quality interfaces can inhibit energy loss from the radiation relaxation of excited species, thereby enhancing the photothermal effect. Here, core-shell structures composed of a covellite (CuS) shell (acceptor) and spherical carbon nanoparticle (CP) core (donor) (abbreviated as CP/CuS) are proposed to augment the photothermal conversion efficiency via the Förster resonance energy transfer (FRET) mechanism. The close proximity and spectral overlap of the donor and acceptor trigger the FRET mechanism, where the electronic excitation relaxation energy of the CP reinforces the plasmonic resonance and near-infrared absorption in CuS, resulting in boosting the overall photothermal conversion efficiency. CP/CuS core-shell coated on polyurethane (PU) foam exhibits a total solar absorption of 97.1%, leading to an elevation in surface temperature of 61.6 °C in dry conditions under simulated solar illumination at a power density of 1 kW m-2 (i.e., 1 sun). Leveraging the enhanced photothermal conversion emanated from the energy transfer effect in the core-shell structure, CP/CuS-coated PU foam achieves an evaporation rate of 1.62 kg m-2 h-1 and an energy efficiency of 93.8%. Thus, amplifying photothermal energy generation in core-shell structures via resonance energy transfer can be promising in solar energy-driven applications and thus merits further exploration.

Facile construction of a robust CuS@NaNbO3 nanorod composite: A unique p-n heterojunction structure with superior performance in photocatalytic hydrogen evolution

The construction of heterojunctions is commonly regarded as an efficient way to promote the production of hydrogen via photocatalytic water splitting through the enhancement of interfacial interactions. The p-n heterojunction is an important kind of heterojunction with an inner electric field based on the different properties of semiconductors. In this work, we reported the synthesis of a novel CuS/NaNbO₃ p-n heterojunction by depositing CuS nanoparticles on the external surface of NaNbO₃ nanorods, using a facile calcination and hydrothermal method. Through the screening of different ratios, the optimum hydrogen production activity reached 1603 μmol·g^-1·h^-1, which is much higher than that of NaNbO₃ (3.6 times) and CuS (2.7 times). Subsequent characterizations proved semiconductor properties and the existence of p-n heterojunction interactions between the two materials, which inhibited the recombination of photogenerated carriers and improved the efficiency of electron transfer. This work provides a meaningful strategy to utilize the p-n heterojunction structure for the promotion of photocatalytic hydrogen production.

In Situ Photodeposition of Cobalt Phosphate (CoHxPOy) on CdIn2S4 Photocatalyst for Accelerated Hole Extraction and Improved Hydrogen Evolution

The ternary metal sulfide CdIn₂S₄ (CIS) has great application potential in solar-to-hydrogen conversion due to its suitable band gap, good stability and low cost. However, the photocatalytic hydrogen (H₂) evolution performance of CIS is severely limited by the rapid electron-hole recombination originating from the slow photogenerated hole transfer kinetics. Herein, by simply depositing cobalt phosphate (CoH_xPO_y, noted as Co-Pi), a non-precious co-catalyst, an efficient pathway for accelerating the hole transfer process and subsequently promoting the H₂ evolution reaction (HER) activity of CIS nanosheets is developed. X-ray photoelectron spectroscopy (XPS) reveals that the Co atoms of Co-Pi preferentially combine with the unsaturated S atoms of CIS to form Co-S bonds, which act as channels for fast hole extraction from CIS to Co-Pi. Electron paramagnetic resonance (EPR) and time-resolved photoluminescence (TRPL) showed that the introduction of Co-Pi on ultrathin CIS surface not only increases the probability of photogenerated holes arriving the catalyst surface, but also prolongs the charge carrier's lifetime by reducing the recombination of electrons and holes. Therefore, Co-Pi/CIS exhibits a satisfactory photocatalytic H₂ evolution rate of 7.28 mmol g^-1 h^-1 under visible light, which is superior to the pristine CIS (2.62 mmol g^-1 h^-1) and Pt modified CIS (3.73 mmol g^-1 h^-1).

Magnetic grinding synthesis of copper sulfide-based photocatalytic composites for the degradation of organic dyes under visible light

CuS based composites prepared by magnetic grinding method with metal and sulfur powder as raw materials have photocatalytic activity.

Semiconductor photocatalysts: A critical review highlighting the various strategies to boost the photocatalytic performances for diverse applications

The photocatalytic technology illustrates an eco-friendly and sustainable route to overcome environmental and energy issues. The successful construction of a photocatalyst depends on four key elements: light absorption ability, the density of active sites, redox capacity, and photoinduced electron-hole recombination rate. Sincemost of intrinsic semiconductor photocatalysts cannot meet all these requirements, they are often modified to boost their photocatalytic properties. Many strategies have been adopted to design novel and efficient photocatalysts for diverse applications. Herein, we review the most efficient of these strategies and methods focused on effectively overcoming the efficiency limitations of photocatalysts to promote their large-scale application. Subsequently, a particular aim is put on the most current studies for photocatalytic applications, including CO₂ reduction, N₂ fixation, H₂ evolution, and pollutants degradation. Finally, key challenges and future perspectives in designing and implementing semiconductor photocatalysts for large-scale applications are discussed. Therefore, it is foreseen that this review will work as a guide for future research and provides a variety of strategies to develop novel and high-performance photocatalysts for various applications.

Co0.9Co0.1S Nanorods with an Internal Electric Field and Photothermal Effect Synergistically for Boosting Photocatalytic H2 Evolution

The paper reports a strategy to synthesize Cd_0.9Co_0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd_0.9Co_0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd_0.9Co_0.1S NRs yield a remarkable H₂ evolution rate of 8.009 mmol·g⁻¹·h⁻¹, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect.

Graphene oxide coupled high-index facets CdZnS with rich sulfur vacancies for synergistic boosting visible-light-catalytic hydrogen evolution in natural seawater: Experimental and DFT study

Constructing photocatalysts with high activity and anti-photocorrosion is a key to harvesting hydrogen energy from seawater efficiently. Herein, graphene oxide closely coupled high-index facets CdZnS with rich sulfur vacancies (Vs-CZS@GO) has been successfully synthesized via one-pot sulfidation accompanied pyrolysis. DFT calculation confirmed the delicate surface/interface/defect engineering endowed high-index facets Vs-CZS@GO with a lower ΔG_H* value and significant charge transfer behavior for efficient H₂-generation. The synergistic effect of sulfur vacancy, high-index facets, and tightly coupling interface not only enhanced intrinsic active sites and carrier separation efficiencies, but also greatly promoted H₂ evolution rate and stability. Consequently, Vs-CZS@GO displayed a significantly high H₂-generation rate of 23.2 mmol∙g^-1∙h^-1 in natural seawater under visible-light irradiation, which is up to 82% of that in pure water. This work provides deeply insight into the synergistic regulation of electronic structure for exposed high-index facets photocatalysts via defect engineering and interface engineering for synergistic boosting visible-light-to-H₂ evolution.

CuS/Ag2O nanoparticles on ultrathin g-C3N4 nanosheets to achieve high performance solar hydrogen evolution

Ternary heterostructures play a crucial role in improving the separation of charge carriers and fast surface reaction kinetics, which in turn helps in understanding the effective photocatalytic water splitting performance. Herein, CuS/Ag₂O nanoparticles were presented on a graphitic carbon nitride (g-C₃N₄) surface to obtain CuS/Ag₂O/g-C₃N₄ material using facile hydrothermal and precipitation methods. Structural and morphological studies confirmed the presence of ternary nanostructures comprising CuS, Ag₂O, and g-C₃N₄ with nanoparticle and nanosheet morphologies. The as-synthesized CuS/Ag₂O/g-C₃N₄ exhibited a remarkable photocatalytic H₂ production of 1752 µmol.h^-1.g^-1_cat, which is considerably superior than those of CuS and g-C₃N₄. The improved H₂ production performance which is due to the effective interfacial CuS/Ag₂O/g-C₃N₄ heterojunction interface and superior hole (h⁺) trapping capability of the CuS at the CuS/Ag₂O/g-C₃N₄ interface. This can efficiently enhance the lifetime of photoexcited charge carriers and enhance the electron density for the production of H₂. The optimum CuS/Ag₂O/g-C₃N₄ heterostructure remained stable after 8 successive experimental cycles, although with a slight change in the H₂ production rate. Therefore, this study offers a novel approach to exploit the efficacy through the synergetic effect of integrating CuS as the photocatalyst and Ag₂O as the visible sensitizer, thus proposing a viable strategy of using earth-abundant material to enhance the conversion of solar energy to fuel.

Synergistic Effect of the Sulfur Vacancy and Schottky Heterojunction on Photocatalytic Uranium Immobilization: The Thermodynamics and Kinetics

Not only a critical matter in the nuclear fuel cycle but uranium is also a global contaminant with both radioactive and chemical toxicity. Reducing soluble hexavalent uranium [U(VI)] to relatively nonimmigrated tetravalent uranium [U(IV)] by photocatalytic technologies is recognized as a highly promising strategy for avoiding environmental pollution and re-extracting uranium resources from nuclear wastewater. Herein, we have designed a heterojunction photocatalyst constructed from the carbon aerogels (CA) and the CdS nanoflowers with an S-vacancy (CA@CdS-SV). With the S-vacancy and heterojunction being synergized, the U(VI) removal rate exceeded 97% in 40 min without the addition of any sacrificial agents. As impacted by the synergistic effects of the S-vacancy and heterojunction, thermodynamics and kinetics revealed that photogenerated electrons were first captured via shallow traps generated by vacancies on CdS-SV and then transferred to the CA surfaces through the heterojunction to realize the spatial separation of carriers, thereby achieving a satisfactory performance. This work is considered to underpin the improvement of U(VI) immobilization by exploiting the synergistic effect of vacancy engineering and the Schottky heterojunction from the perspective of thermodynamics and kinetics.

Facile synthesis of compact CdS−CuS heterostructures for optimal CO2−to−syngas photoconversion

Herein, a facile two−step synthetic pathway was developed to construct compact CdS−CuS heterostructures for syngas production via CO2 photoreduction. The photocatalytic activity of CdS−CuS−2 was testified with a syngas yield...

Core–shell Cu1.94S–MnS nanoheterostructures synthesized by cation exchange for enhanced photocatalytic hydrogen evolution

The nanoheterostructures synthesized by cation exchange present the integration of synergetic designs into high-quality, well-defined catalysts for enhanced photocatalytic hydrogen evolution.