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Today, as a result of the advancement of technology and increasing environmental problems, the need for clean energy has considerably increased. In this regard, hydrogen, which is a clean and sustainable energy carrier with high energy density, is among the well-regarded and effective means to deliver and store energy, and can also be used for environmental remediation purposes. Renewable hydrogen energy carriers can successfully substitute fossil fuels and decrease carbon dioxide (CO2) emissions and reduce the rate of global warming. Hydrogen generation from sustainable solar energy and water sources is an environmentally friendly resolution for growing global energy demands. Among various solar hydrogen production routes, semiconductor-based photocatalysis seems a promising scheme that is mainly performed using two kinds of homogeneous and heterogeneous methods, of which the latter is more advantageous. During semiconductor-based heterogeneous photocatalysis, a solid material is stimulated by exposure to light and generates an electron–hole pair that subsequently takes part in redox reactions leading to hydrogen production. This review paper tries to thoroughly introduce and discuss various semiconductor-based photocatalysis processes for environmental remediation with a specific focus on heterojunction semiconductors with the hope that it will pave the way for new designs with higher performance to protect the environment. [ABSTRACT FROM AUTHOR]

Developing interfacial connections is one of the breakthrough strategies to improve the photocatalytic activity. Herein, ZnBi 2 O 4 nanoparticles-ZnO nanorods heterojunction was successfully synthesized and used, as a dual-function photocatalyst, for photocatalytic degradation of Bisphenol A and hydrogen production with improved photocatalytic activity under simulated sunlight irradiation. The highest H 2 production (3.44 mmol g−1 h−1) was obtained for ZnO-20 wt% ZnBi 2 O 4 sample, which is around 12.7 times higher than pure ZnO. According to the HRTEM result, the intimate interfacial connections are formed between ZnO and ZnBi 2 O 4 which could act as trapping centers for charge carriers and results in the boosted photocatalytic activity. Further, a high aspect ratio of 1D ZnO nanorods and small size of 0D ZnBi 2 O 4 nanoparticles (~10 nm) increases the number of interfacial contacts and thus the charge carriers' recombination was suppressed more efficiently. Based on the trapping experiments, ESR and Mott-Schottky analysis, ZnBi 2 O 4 –ZnO hybrid photocatalyst followed the S -scheme charge transfer mechanism. • Novel 0D/1D ZnBi 2 O 4 /ZnO p-n heterojunction was successfully prepared. • The prepared hybrid system revealed improved H 2 production and BPA decomposition. • The highest hydrogen evolution (3.44 mmol.g−1.h−1) was achieved on ZnO–20%ZnBi 2 O 4. • S -scheme mechanism was suggested for boosted photocatalytic activity. • The defects formed at the interfacial contacts decreased the recombination rate. [ABSTRACT FROM AUTHOR]

• V-doped Ni-Mo-P nanostructure was fabricated using electrochemical deposition. • Fabricated electrode exhibited outstanding electrocatalytic HER and OER activity. • Synergistic effect and high surface area was main reason for excellent performance. • Deposited electrode represented outstanding electrocatalytic durability. The emergence and fabrication of cost-effective and active electrodes in the overall water splitting process are one of the most critical challenges for hydrogen production. Here, firstly Ni-P electrodes were generated at different scan rates using the electrochemical deposition method, and then molybdenum was doped in Ni-P structure using the same method and vanadium using hydrothermal deposition method, and V-doped Ni-Mo-P electrode was generated. It was revealed that the synthesized electrode displays outstanding electrochemical properties for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). For reaching a current density of 10 mA cm −2, the optimum sample needed only 65 mV in the HER process and only 261 mV of overpotential in the OER process. In addition, the electrocatalytic stability investigation disclosed that this electrode had excellent durability at the 100 mA cm −2 in HER and OER process after 10 h of electrolysis in which only less than 2 % increase in overpotential was observed, which indicates excellent electrocatalytic stability. Such outstanding electrocatalytic properties were mainly because of increasing the active surface area and the synergistic effect due to doping of molybdenum and vanadium in the electrode structure. [ABSTRACT FROM AUTHOR]

• Au/Ce/SnS 2 /HPEI nanocomposite was obtained via a wet/hydrothermal method. • Au/Ce/SnS 2 /HPEI had high activity and good stability in photocatalytic process. • Investigation of synergistic effects of catalyst for H 2 production processes. • The prepared Au/Ce/SnS 2 /HPEI displayed excellent antifungal activity. In this project, the Au and Ce co-doped SnS 2 decoration on hyperbranched polyethyleneimine (Au/Ce/SnS 2 /HPEI) nanocomposites were prepared via wet/hydrothermal chemical method. Compared with pure SnS 2 and co doped SnS 2 , Au/Ce/SnS 2 /HPEI nanocomposite indicated higher photo-degradation performance for the reduction of chromium (VI) under visible light irradiation. Therewith, Au/Ce/SnS 2 /HPEI nanocomposites was applied for photo-degradation of drug. The possible mechanism shows the superoxide anion radical (O 2 −) plays important role in in the removal of Cr(VI). The Au/Ce/SnS 2 /HPEI nanocomposites shows the best photocatalysis activity for water reduction. The prepared Au/Ce/SnS 2 /HPEI displayed excellent antifungal activity against Aspergillus niger and Candida albicans fungi. [ABSTRACT FROM AUTHOR]