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Leveraging solar energy through photocatalytic hydrogen production from water stands out as one of the most promising approaches to address the energy and environmental challenges. The choice of catalyst profoundly influences the outcomes of photocatalytic reactions, and constructing heterojunctions has emerged as a widely applied strategy to overcome the limitations associated with single-phase photocatalysts. MoO3, renowned for its high chemical stability, encounters issues such as low photocatalytic efficiency and fast recombination of photogenerated electrons and holes. To tackle these challenges, the morphology of MoO3 has been controlled to form nanorods, simultaneously suppressing the aggregation of the catalyst and increasing the number of surface-active sites. Moreover, to facilitate the separation of photogenerated charge carriers, Cd0.9Zn0.1S nanoparticles with a twin crystal structure are deposited on the surface of MoO3, establishing an S-scheme heterojunction. Experimental findings demonstrate that the synergistic effects arising from the well-defined morphology and interface interactions extend the absorption range to visible light response, improve charge transfer activity, and prolong the lifetime of charge carriers. Consequently, Cd0.9Zn0.1S/MoO3 S-scheme heterojunctions exhibit outstanding photocatalytic hydrogen production performance (3909.79 μmol g−1 h−1) under visible light irradiation, surpassing that of MoO3 by nearly nine fold. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic performance of semiconductor catalysts, one of the most widely used strategies is to combine two or more semiconductors with appropriate energy band structures to construct heterojunctions for an extended light absorption range and effective charge separation. Here, a novel Z-scheme heterojunction is fabricated via the Cd0.3Zn0.7S twin crystal and the narrow band gap semiconductor Ag3PO4. The resulting Cd0.3Zn0.7S/1%Ag3PO4 photocatalyst exhibits excellent photocatalytic hydrogen production capability (167.29 μmol h−1), which is two times higher than that of Cd0.3Zn0.7S and 44/7 times higher than that of pristine ZnS/CdS. The excellent photocatalytic performance is not only attributed to the defective twin crystal structure of Cd0.3Zn0.7S but also related to the well-matched Z-scheme interface between Cd0.3Zn0.7S and Ag3PO4, and both factors effectively promote the separation of the photogenerated electron–hole pairs and prolong the lifetime of the carriers, being responsible for the excellent photocatalytic hydrogen evolution performance of the catalysts. This strategy provides new insights into the construction of efficient twin crystal heterojunctions for photocatalytic hydrogen evolution with high performance. [ABSTRACT FROM AUTHOR]

Defects engineering is significant for photocatalytic environment remediation. To this end, visible‐light‐driven α‐Fe2O3/ZrO2‐x S‐scheme heterojunction photocatalysts with optimal oxygen vacancy (Ov) defects are successfully synthesized via a two‐step method. Compared with pristine UiO‐66‐NH2‐derived ZrO2‐x and α‐Fe2O3, the heterojunction photocatalysts exhibit a wider range of visible light response and higher efficiency in separating photogenerated electron–hole pairs. Among them, the 5% α‐Fe2O3/ZrO2‐x sample shows the best photocatalytic performance to the degradation of tetracycline (TC) (89.3%), in which the pseudo‐first‐order kinetic rate constants are 8.20 and 16.75 times that of pristine ZrO2‐x and α‐Fe2O3, respectively. The outstanding photocatalytic degradation efficiency can be attributed to both the narrow‐bandgap ZrO2‐x with visible light response and the formation of α‐Fe2O3/ZrO2‐x S‐scheme heterojunctions. During the formation of heterojunctions, the concentration of oxygen vacancies (Ov) at the interface of α‐Fe2O3/ZrO2‐xdecreases monotonically with the increasing loading of α‐Fe2O3, thereby altering the electronic structure of the photocatalyst and forming the heterojunction firmly. In addition, the high stability implies the potential applications in fields of environment. [ABSTRACT FROM AUTHOR]

Designing titanium-based oxides with efficient photogenerated carrier separation is an essential approach to enhance their photocatalytic hydrogen production performance. ALiTi 3 O 7 possesses excellent stability, corrosion resistance, and non-toxicity. More importantly, its stoichiometry can be changed along with the variations in A-site elements and Li content, leading to tunable redox potentials of the conduction band minimum (CBM) and valence band maximum (VBM). Exploring the possible application of such materials in the field of photocatalysis is crucial for developing novel and efficient titanium-based photocatalysts. As a member of the family, NaLiTi 3 O 7 (NLT) has a large bandgap, limiting its application as visible light photocatalyst. To address this issue, non-toxic La 2 S 3 (LS) narrow-bandgap semiconductor was incorporated to form a heterojunction. The characterization techniques have revealed the structural and interfacial characteristics of the NLT-LS heterojunction, while the Infrared, Raman, UV–Vis diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), and work-function tests elucidated the influence of the interface interaction on charge carrier separation mechanism. The test results further demonstrated that the formation of a type II heterojunction facilitated the transfer of photogenerated electrons from the conduction band of LS to the conduction band of NLT under light radiation. Simultaneously, the induced holes were confined to the valence band of LS. This charge transfer characteristic significantly improved the separation efficiency of the photogenerated carriers in the heterojunction, ultimately resulting in a photocatalytic hydrogen production rate of 102.4 μmol h−1 g−1 for the NLT-LS2 sample, which is ∼8 times higher than that of pure NLT and almost no decay after four cycles. • A novel and very stable photocatalyst based on NaLiTi 3 O 7 and La 2 S 3 were successfully constructed. • The type-II heterojunctions have extended light adsorption capability and promising charge separation efficiency. • The photocatalytic production rate of H 2 reaches 102.4 μmol h−1 g−1. • Demonstration of NaLiTi 3 O 7 as a promising photocatalyst is important for the design of novel Ti-based oxides. [ABSTRACT FROM AUTHOR]

Mesoporous TiO 2 nanospheres with engineered surface defects are fabricated through surfactant-mediated self-assembly solvothermal approach combined with surface hydrogenation, which exhibit excellent solar-driven photocatalytic hydrogen evolution, due to surface defects induced charge imbalance improving charge separation, and unique spherical mesoporous structure supplying adequate surface-active sites and facilitating mass transfer. [Display omitted] • Surface defects induced charge imbalance promote charge separation. • Mesoporous TiO 2 nanospheres with engineered surface defects are fabricated. • Nanoscale mesoporous spheres have closed packing and low surface energy. • It exhibits excellent solar-driven photocatalytic H 2 evolution and high stability. • Surface defects and mesostructure favor charge separation and mass transfer. Low charge separation efficiency of semiconductor materials is the main obstacle for high-performance photocatalyst. Herein, we report surface defects engineered uniform mesoporous TiO 2 nanospheres (DMTNSs) through surfactant-mediated self-assembly solvothermal approach combined with hydrogenation strategy to promote charge separation. The surface defects induced charge imbalance result in the formation of built-in field, which can promote photogenerated charge separation efficiently and be confirmed by experimental and density functional theory (DFT) calculations. Under AM 1.5G irradiation, the photocatalytic hydrogen evolution of DMTNSs is ~3.34 mmol h−1 g−1, almost 3.5 times higher than that of pristine non-defective TiO 2 nanospheres (0.97 mmol h−1 g−1), due to the engineered surface defects narrowing the bandgap (~3.01 eV) and inducing charge imbalance to boost spatial charge separation and extend visible-light response. The defect induced charge imbalance strategy opens a new valuable perspective for fabricating other high-efficient oxide photocatalysts. [ABSTRACT FROM AUTHOR]

Oxygen-defective Bi 2 MoO 6 /g-C 3 N 4 hollow tubulars S-scheme heterojunctions are fabricated by hydrothermal and calcination methods and show excellent photocatalytic performance. The S-Scheme heterojunction accelerates the effective charge separation and transfer by internal electric field (IEF) and energy band bending at the interface, thus improving the photocatalytic performance. [Display omitted] Novel S-scheme heterojunction photocatalysts of bismuth molybdate/hollow tube graphite carbon nitride (Bi 2 MoO 6 SOVs/g-C 3 N 4) containing surface defects (SOVs) were prepared by calcination and hydrothermal methods. The hollow tubular structure of g-C 3 N 4 facilitates the enhancement of multiple reflection and scattering of light, and also have a larger range of specific surface areas and more reactive sites, which promotes carrier separation and thus improves photocatalytic performance. The introduction of SOVs to bismuth molybdate not only reduces the band gap of bismuth molybdate, but also promotes the separation of charges. The optimized Bi 2 MoO 6 SOVs/TCN photocatalyst has a hydrogen production efficiency of 2.29 mmol h−1 g−1. It also shows high photocatalytic degradation property of tetracycline and bisphenol A in water, up to 97.3 % and 98.9 %, respectively. Meanwhile, the transfer mechanism of photogenerated charges in S-scheme heterojunctions can be verified by electron paramagnetic resonance and in situ irradiated x-ray photoelectron spectroscopy electron paramagnetic resonance, which accelerated the separation and transfer of photogenerated charge by energy band bending at the interface and internal electric field. This rational structural design strategy provides a new development idea for building high-performance S-scheme heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

• The 2D porous Ni/NiMoN heterojunction nanobelts catalysts with tunable components were designed and synthesized. • The 2D porous Ni/NiMoN heterojunction have good ability for mass/charge transfer and optimized electronic structure for H* adsorption. • The Ni/NiMoN catalyst exhibits excellent HER activity and durability with low overpotential of 48 mV at 10 mA cm−2. • The electrolyzer composed of 2D Ni/NiMoN catalyst and matched OER catalyst only requires a low cell voltage of 1.47 V to attain 10 mA cm−2 with excellent durability for 96 h. • The origin of superior performance of the heterostructures is elucidated by combining density functional theory calculations and work function test etc. The design of the electrocatalysts with the plentiful heterojuctional interface and large-accessible surface is desired to boost the HER performance, but it remains a challenge. Herein, we showed the design of 2D Ni/Ni 0.2 Mo 0.8 N porous heterojunction nanobelts as effective catalyst for the HER. The intimate combination of Ni and Ni 0.2 Mo 0.8 N can make the formation of the heterojuctional interface with plentiful active sites. The 2D porous structure can provide large accessible surface with less resistance for the transmission of the electrolytes, thus promoting the mass/charge transfer. The ratio of Ni and Ni 0.2 Mo 0.8 N can be easily tuned by regulating the precursor composition, which is important to give catalysts with optimized interface and suitable pores. Density functional theory calculations reveal that the interaction between Ni and Ni 0.2 Mo 0.8 N at the heterointerface can largely improve the intermediate H* adsorption kinetics (ΔG H* = -0.07 eV). Due to the above advantages, the optimized catalysts exhibited excellent HER activity with a low overpotential of 48 mV in 1 M KOH at 10 mA cm−2 (without iR correction), which is superior to the most reported non-noble metal-based catalysts, and the long-term durability with no obvious degradation after continual operation of 48 h Notably, an electrolyzer assembled by the optimized Ni/Ni 0.2 Mo 0.8 N cathode with NiFe-LDH anode only requires a low operating voltage of 1.47 V to deliver 10 mA cm−2 in 1 M KOH, surpassing the corresponding Pt/NF||RuO 2 /NF electrolyzer (1.61 V) and most of reported electrolyzers. The 2D porous Ni/NiMoN heterojunction nanobelts were successfully obtained as highly effective hydrogen evolution electrocatalysts. Benefiting from the redistribution of electrons at the interface and the porous structure, the catalyst exhibits excellent HER activity and durability, affording low overpotential of only 48 mV at 10 mA cm−2. The Ni/NiMoN heterojunction catalyst can match well with an appropriate OER catalyst to realize overall water splitting, only requiring a cell voltage of 1.47 V to achieve 10 mA cm−2 with excellent durability for 96 h, surpassing the corresponding Pt/C/NF||RuO 2 /NF electrolyzer (1.61 V) and most of recently reported Ni/Mo-based compounds. [Display omitted] [ABSTRACT FROM AUTHOR]