A novel p–n heterojunction Mn 0.25 Cd 0.75 S/Co 3 O 4 for highly efficient photocatalytic H 2 evolution under visible light irradiation

Uniform H-CdS@NiCoP core-shell nanosphere for highly efficient visible-light-driven photocatalytic H2 evolution

Constructing highly efficient and cost-effective photocatalyst system has been a big challenge for photocatalysis. Herein, CdS nanosphere (N-CdS), hollow CdS (H-CdS) and a series of H-CdS@NiCoP core-shell nanospheres have been successfully prepared via a facile hydrothermal method. The activity test showed that H-CdS exhibited higher photocatalytic activity (3.34 mmol g^-1h^-1) compared with N-CdS (0.99 mmol g^-1h^-1) under visible light irradiation (λ ≥ 420 nm), suggesting that hollow structure could effectively improve photocatalytic activity. Moreover, the H-CdS@NiCoP-7 wt% displayed a maximum photocatalytic H₂ evolution rate of 13.47 mmol g^-1h^-1, which was about 4 times and 2.5 times higher than that of pristine H-CdS and H-CdS@Pt-3 wt%, respectively. Furthermore, H-CdS@NiCoP-7 wt% exhibited a good stability during 20 h test. The physicochemical properties were characterized by XRD, SEM, TEM, XPS, UV-vis DRS, PL and photoelectrochemical technique. The results showed that NiCoP addition can construct p-n junction with H-CdS and effectively promote the charge transfer from CdS to NiCoP, which improved the photocatalytic hydrogen evolution activity. This work revealed that NiCoP could react as an excellent co-catalyst for enhancing H-CdS photocatalytic activity.

Modification of the surface of Mn0.25Cd0.75S polyhedra with NiB: reducing the surface work function and promoting electron migration for enhanced photocatalytic hydrogen production

NiB is compounded on the surface of Mn0.25Cd0.75S to bring them into close contact. The photocatalytic hydrogen production rate of 10% NiB/Mn0.25Cd0.75S is 13.06 mmol g−1 h−1, which is 3.7 times higher than that of pure Mn0.25Cd0.75S.

Interface engineering of Co9S8/CdIn2S4 ohmic junction for efficient photocatalytic H2 evolution under visible light

The design and development of high-performance photocatalysts from three aspects of simultaneous enhancement of light harvest, carrier migration rate, and redox reaction rate is still a great challenge. Herein, a novel Co₉S₈/CdIn₂S₄ ohmic junction with a robust internal electric field (IEF) is successfully prepared via hydrothermal and in situ synthesis methods and is used for effective photocatalytic H₂ evolution (PHE). Under simulated visible light irradiation, the PHE rate of 5% Co₉S₈/CdIn₂S₄ can reach 1083.6 μmol h^-1 g^-1, which is 6.4 times higher than that of CdIn₂S₄ (170.5 μmol h^-1 g^-1). The enhanced PHE performance is mainly ascribed to the improved light harvest and carrier separation efficiency and fast surface H₂ evolution kinetics. Moreover, Co₉S₈ nanotubes serve as promising Co-based cocatalysts that can evidently enhance PHE activity. Additionally, Co₉S₈/CdIn₂S₄ shows superior stability because the photogenerated carrier transfer path restrains the photocorrosion behavior. The photocatalytic mechanism is proposed based on experimental results and DFT calculations. This work offers new insights for the design and development of highly active photocatalysts from interface engineering.

Recent advances in Co-based co-catalysts for efficient photocatalytic hydrogen generation

Recent progress in photocatalytic hydrogen generation reaction highlights the critical role of co-catalysts in enhancing the solar-to-fuel conversion efficiency of diverse band-matched semiconductors. Because of the compositional flexibility, adjustable microstructure, tunable crystal phase and facet, cobalt-based co-catalysts have stimulated tremendous attention as they have high potential to promote hydrogen evolution reaction. However, a comprehensive review that specifically focuses on these promising materials has not been reported so far. Therefore, this present review emphasizes the recent progress in the pursuing of highly efficient Co-based co-catalysts for water splitting, and the advances in such materials are summarized through the analysis of structure-activity relationships. The fundamental principles of photocatalytic hydrogen production are profoundly outlined, followed by an elaborate discussion on the crucial parameters influencingthe reaction kinetics. Then, the co-catalytic reactivities of various Co-based materials involving Co, Co oxides, Co hydroxides, Co sulfides, Co phosphides and Co molecular complexes, etc, are thoroughly discussed when they are coupled with host semiconductors, with an insight towards the ultimateobjective of achieving a rationally designed photocatalyst for enhancing water splitting reaction dynamics. Finally, the current challenge and future perspective of Co-based co-catalysts as the promising noble-metal alternative materials for solar hydrogen generation are proposed and discussed.

Visible-light-driven two dimensional metal-organic framework modified manganese cadmium sulfide for efficient photocatalytic hydrogen evolution

The morphology modification and the construction of heterojunction of the photocatalyst are considered as the main means to significantly improve the performance of photocatalytic hydrogen evolution. In this study, Mn_0.2Cd_0.8S nanorods are successfully assembled on the surface of Ni-MOF-74 with flake morphology. Specifically, the Ni-S bond is constructed between Ni-MOF-74 and Mn_0.2Cd_0.8S, which provides a unique transfer channel for photo-induced carriers. Meanwhile, the electrons in the conduction band of Mn_0.2Cd_0.8S can be injected into the conduction band of Ni-MOF-74 quickly due to the potential energy difference between the two. This shows that the recombination of photogenerated carriers in Mn_0.2Cd_0.8S can be greatly inhibited. Fluorescence spectroscopy and electrochemical characterization reveal that the composite catalyst has the longest carrier lifetime, the fastest charge transfer rate and the lowest overpotential compared with the Mn_0.2Cd_0.8S and Ni-MOF-74. The optimal hydrogen production rate of the composite can reach 7.104 mmol g^-1h^-1, which is 6.96 times that of Mn_0.2Cd_0.8S. This work provides a novel strategy for the modification of MnCdS-based photocatalysts by metal-organic framework materials.

Efficient hydrogen production at a rationally designed MoSe2@Co3O4 p-n heterojunction

During the past several years, transition metal compounds have shown high activity in the field of photocatalysis. Therefore, the MoSe₂@Co₃O₄ with excellent photocatalytic properties through simple hydrothermal and physical mixing methods was prepared. This composite material was composed of n-type semiconductor MoSe₂ and p-type semiconductor Co₃O₄. After optimizing the loading of Co₃O₄, the optimal hydrogen production can reached 7029.2 μmol g^-1h^-1, which was 2.34 times that of single MoSe₂. In addition, some characterization methods were used to explore the hydrogen production performance of the composite catalyst under EY sensitized conditions. Among them, the UV-vis diffuse reflectance spectra suggests that MoSe₂@Co₃O₄ exhibits stronger visible light absorption performance than the single material. Fluorescence performance and photoelectrochemical characterization experiments further prove that, the special structure formed by MoSe₂ and Co₃O₄ and the existence of p-n heterojunction effectively accelerate the separation and transfer of carriers meanwhile inhibit the recombination probability of electron-hole pairs. Combined with other characterizations such as XRD, XPS, SEM and BET, the possible hydrogen production mechanism was proposed.

p-n Heterojunction Photocatalyst Mn0.5Cd0.5S/CuCo2S4 for Highly Efficient Visible Light-Driven H2 Production

It is highly important to develop efficient and cheap photocatalysts for hydrogen production. Herein, a series of p-n heterojunction Mn_0.5Cd_0.5S/CuCo₂S₄ has been successfully synthesized for the first time by the hydrothermal impregnation method. Mn_0.5Cd_0.5S/CuCo₂S₄ loading with 12 wt % CuCo₂S₄ shows the highest H₂ evolution rate of 15.74 mmol h^-1 g^-1 under visible light (λ ≥ 420 nm) irradiation, which is about 3.15 and 15.28 times higher than that of bare Mn_0.5Cd_0.5S (4.99 mmol h^-1 g^-1) and CuCo₂S₄ (1.03 mmol h^-1 g^-1), respectively. In addition, it shows a relatively good stability during the five recycle tests, with about 20% loss of reaction rate compared to that of the first cycle. The superior photocatalytic performance is attributed to the effective separation and transfer of photogenerated charge carriers because of the formation of the p-n junction. The samples are systematically characterized by X-ray diffraction, ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, photoluminescence, EIS, and so on. UV-vis and EIS show that CuCo₂S₄ can effectively improve the visible light response of Mn_0.5Cd_0.5S/CuCo₂S₄ and promote the electron transfer from CuCo₂S₄ to the conduction band of Mn_0.5Cd_0.5S, so as to improve the photocatalytic efficiency. This study reveals that the p-n heterojunction Mn_0.5Cd_0.5S/CuCo₂S₄ is a promising photocatalyst to explore the photocatalysts without noble metals.

A novel p-n Mn0.2Cd0.8S/NiWO4 heterojunction for highly efficient photocatalytic H2 production

Constructing a p-n heterojunction has been regarded as an effective way to restrain charge recombination and boost photocatalytic H2 production activity. Herein, a novel Mn0.2Cd0.8S/NiWO4 composite was fabricated by a hydrothermal process and which exhibited enhanced H2 production activity and excellent photostability. Particularly, the composite with 30 wt% of NiWO4 achieved the optimal H2 production rate of 17.76 mmol g-1 h-1, which was 2.9 times higher than that of Mn0.2Cd0.8S. The increased H2 production property was mainly due to the p-n heterojunction between Mn0.2Cd0.8S and NiWO4, which provided an efficient path for charge transfer and inhibited the photocorrosion of Mn0.2Cd0.8S. This work can offer technical support for the design and development of p-n heterojunctions that can be applied for photocatalytic H2 production.

MoS2-wrapped Mn0.2Cd0.8S nanospheres towards efficient photocatalytic H2 generation and CO2 reduction

MoS₂-wrapped Mn_0.2Cd_0.8S nanospheres with intimate interfacial contacts were fabricated, and exhibited excellent photocatalytic performances for H₂-generation and CO₂ reduction.

Simultaneous manipulation of ion doping and cocatalyst loading into Mn0.3Cd0.7S nanorods toward significantly improved H2 evolution

Ni₂P and Ni²⁺ jointly modified Mn_0.3Cd_0.7S photocatalysts were successfully fabricated via a facile solvothermal method. The loading of Ni₂P and the doping of Ni²⁺ proceeded simultaneously via a one-step process.

Synthesis of MnxCd1−xS nanorods and modification with CuS for extraordinarily superior photocatalytic H2 production

A series CuS/Mn_0.3Cd_0.7S photocatalysts with nanorod structures were successfully constructed and exhibited particularly high H₂ evolution performance from water splitting under visible light irradiation.

One-pot hydrothermal synthesis of MoS2-modified Mn0.5Cd0.5S solid solution for boosting H2 production activity under visible light

Mn_xCd_1−xS solid solutions are obtained, and Mn_0.5Cd_0.5S exhibits the best H₂ production activity, which was further boosted by MoS₂-loading.