Self-assembled Transition Metal Chalcogenides@CoAl-LDH 2D/2D Heterostructures with Enhanced Photoactivity for Hydrogen Evolution

Transition metal chalcogenides (TMCs) have been well-established as ideal low-dimensional systems for photocatalytic hydrogen evolution. Strategies toward improving the activity of these TMCs photocatalysts by crafting heterostructures have been intensively...

CdS/MnS p-n heterojunction with directional carriers diffusion path for efficient photocatalytic H2 production

Photocatalytic reactions usually involve the reduction of photogenerated electrons and the oxidation of photogenerated holes. The migration process of photongenerated holes is slower than photogenerated electronics, and the oxidation potential...

Recent Status and Challenges in Multifunctional Electrocatalysis Based on 2D MXenes

Due to their chemical and electrical characteristics, such as metallic conductivity, redox-activity in transition metals, high hydrophilicity, and adjustable surface properties, MXenes are emerging as important contributors to oxygen reduction...

Bioinspired spike-like double yolk–shell structured TiO2@ZnIn2S4 for efficient photocatalytic CO2 reduction

A spike-like double yolk–shell structured TiO2@ZnIn2S4 (D-Y-TiO2@ZnIn2S4) photocatalyst was designed, which possesses superior photocatalytic CO2 reduction efficiency.

Facile synthesis of porous 3D honeycomb-like ZnIn2S4 microspheres with improved photocatalytic activity for hydrogen evolution

The synthesized 3D honeycomb-like ZnIn2S4 microspheres exhibited good hydrogen production performance under simulated sunlight.

Unique Cd0.5Zn0.5S/WO3-x direct Z-scheme heterojunction with S, O vacancies and twinning superlattices for efficient photocatalytic water-splitting

Photocatalytic water-splitting employing the Z-scheme semiconductor systems mimicking natural photosynthesis is regarded as a promising way to achieve efficient soalr-to-H₂ conversion. Nevertheless, it still remains a big challenge to design high-performance direct Z-scheme photocatalysts without the use of noble metals as electron mediators. Herein, a unique Cd_0.5Zn_0.5S/WO_3-x direct Z-scheme heterojunction was constructed for the first time, which consisted of smaller O-vacancy-decorated WO_3-x nanocrystals anchoring on Cd_0.5Zn_0.5S nanocrystals with S vacancies and zinc blende/wurtzite (ZB/WZ) twinning superlattices. Under visible-light (λ > 420 nm) irradiation, the Cd_0.5Zn_0.5S/WO_3-x composites exhibited an outstanding H₂ evolution reaction (HER) activity of 20.50 mmol h^-1 g^-1 (corresponding to the apparent quantum efficiency of 18.0% at 420 nm), which is much superior to that of WO_3-x, Cd_0.5Zn_0.5S, and Cd_0.5Zn_0.5S loaded with Pt. Interestingly, the introduced O and S vacancies contributed to improving the HER activity of Cd_0.5Zn_0.5S/WO_3-x significantly. Moreover, the cycling and long-term HER measurements confirmed the robust photocatalytic stability of Cd_0.5Zn_0.5S/WO_3-x for H₂ production. The excellent light harvesting and efficient spatial charge separation induced by the ZB/WZ twinning homojunctions and defect-promoted direct Z-scheme charge-transfer pathway are responsible for the exceptional HER capability. Our study could enlighten the rational engineering and optimization of semiconductor nanostructures for energy and environmental applications.

Cu2O/CeO2 Photoelectrochemical Water Splitting: A Nanocomposite with an Efficient Interfacial Transmission Path under the Co-action of p-n Heterojunction and Micro-mesocrystals

Cu 2 O is an ideal p-type material for photoelectrochemical (PEC) hydrogen evolution, while serious electron-hole recombination and photocorrosion restrict its further improvement of the PEC activity. In this work, CeO 2 nanoparticles (NPs) self-assemble on the Cu 2 O octahedra surface, successfully constructing Cu 2 O/CeO 2 structure in which p-n heterojunction and micro-mesocrystals (m-MCs) structure work together. The optimum Cu 2 O/CeO 2 composite without the use of any cocatalyst exhibits 5 times higher photocurrent density (4.63 mA cm -2 at 0 V versus the reversible hydrogen electrode) than that of Cu 2 O octahedra, which is better than most Cu 2 O-based photocathodes without cocatalyst and even comparable with the advanced Cu 2 O-based photocathodes. The hydrogen production of the optimal Cu 2 O/CeO 2 (Faradaic efficiency of ~100%) is 17.5 times higher than that of pure Cu 2 O octahedra and the photocurrent shows almost no decay under the 12 h stability test. The delicately designed Cu 2 O/CeO 2 structure in this work provides reference and inspiration for the design of cathodes materials.

Crystallinity-dependent photodegradation of metallic Bi in situ grown on perovskite Bi3TiNbO9 nanosheets toward antibiotic

Owing to its wide band gap of ~3.2 eV, perovskite Bi₃TiNbO₉ only absorbs the solar spectrum in the ultraviolet range, which restricts its use as an effective photocatalyst. Here, a controllable and facile reduction strategy was adopted to promote the in-situ growth of metallic Bi in perovskite Bi₃TiNbO₉ nanosheets. The in-situ growth of metallic Bi extended photoresponse to cover the whole visible region. Adsorption of tetracycline hydrochloride (TC-H) on the surface of Bi₃TiNbO₉ with in-situ growth of metallic Bi (BTNO_OV-Bi⁰) was dramatically enhanced, while BTNO_OV-Bi⁰ exhibited a superior photocatalytic performance for tetracycline hydrochloride (TC-H) degradation under visible light irradiation with the degradation rate of 5 times higher than that of pristine Bi₃TiNbO₉. Moreover, the degradation activity was strongly dependent on the crystallinity of metallic Bi phase in BTNO_OV-Bi⁰ samples. On the basis of experiment results, the visible-light driven catalytic mechanism of BTNO_OV-Bi⁰ was elucidated. Besides, the in-situ growth of metallic Bi was also introduced in perovskite Bi₅FeTi₃O₁₅, resulting in an enhanced photocatalytic activity, which indicated an enormous potential of this strategy in semiconductor structure tuning. Our study provides an effective approach to boost the performance of photocatalysts for solar-energy conversion.

CdIn2S4/In(OH)3/NiCr-LDH Multi-Interface Heterostructure Photocatalyst for Enhanced Photocatalytic H2 Evolution and Cr(VI) Reduction

The development of highly active and stable photocatalysts, an effective way to remediate environment pollution and alleviate energy shortages, remains a challenging issue. In this work, a CdIn2S4/In(OH)3 nanocomposite was deposited in-situ on NiCr-LDH nanosheets by a simple hydrothermal method, and the obtained CdIn2S4/In(OH)3/NiCr-LDH heterostructure photocatalysts with multiple intimate-contact interfaces exhibited better photocatalytic activity. The photocatalytic H2 evolution rate of CdIn2S4/In(OH)3/NiCr-LDH increased to 10.9 and 58.7 times that of the counterparts CdIn2S4 and NiCr-LDH, respectively. Moreover, the photocatalytic removal efficiency of Cr(VI) increased from 6% for NiCr-LDH and 75% for CdIn2S4 to 97% for CdIn2S4/In(OH)3/NiCr-LDH. The enhanced photocatalytic performance was attributed to the formation of multi-interfaces with strong interfacial interactions and staggered band alignments, which offered multiple pathways for carrier migration, thus promoting the separation efficiency of photo-excited electrons and holes. This study demonstrates a facile method to fabricate inexpensive and efficient heterostructure photocatalysts for solving environmental problems.

Emerging Cocatalysts on g-C3 N4 for Photocatalytic Hydrogen Evolution

Over the past few decades, graphitic carbon nitride (g-C₃ N₄ ) has arisen much attention as a promising candidate for photocatalytic hydrogen evolution reaction (HER) owing to its low cost and visible light response ability. However, the unsatisfied HER performance originated from the strong charge recombination of g-C₃ N₄ severely inhibits the further large-scale application of g-C₃ N₄ . In this case, the utilization of cocatalysts is a novel frontline in the g-C₃ N₄ -based photocatalytic systems due to the positive effects of cocatalysts on supressing charge carrier recombination, reducing the HER overpotential, and improving photocatalytic activity. This review summarizes some recent advances about the high-performance cocatalysts based on g-C₃ N₄ toward HER. Specifically, the functions, design principle, classification, modification strategies of cocatalysts, as well as their intrinsic mechanism for the enhanced photocatalytic HER activity are discussed here. Finally, the pivotal challenges and future developments of cocatalysts in the field of HER are further proposed.

ZnIn2 S4 -Based Photocatalysts for Energy and Environmental Applications

As a fascinating visible-light-responsive photocatalyst, zinc indium sulfide (ZnIn₂ S₄ ) has attracted extensive interdisciplinary interest and is expected to become a new research hotspot in the near future, due to its nontoxicity, suitable band gap, high physicochemical stability and durability, ease of synthesis, and appealing catalytic activity. This review provides an overview on the recent advances in ZnIn₂ S₄ -based photocatalysts. First, the crystal structures and band structures of ZnIn₂ S₄ are briefly introduced. Then, various modulation strategies of ZnIn₂ S₄ are outlined for better photocatalytic performance, which includes morphology and structure engineering, vacancy engineering, doping engineering, hydrogenation engineering, and the construction of ZnIn₂ S₄ -based composites. Thereafter, the potential applications in the energy and environmental area of ZnIn₂ S₄ -based photocatalysts are summarized. Finally, some personal perspectives about the promises and prospects of this emerging material are provided.

Constructing a Z-scheme ZnIn2S4-S/CNTs/RP nanocomposite with modulated energy band alignment for enhanced photocatalytic hydrogen evolution

Energy band structures greatly determine the charge separation and transfer properties in heterojunction photocatalysts and consequently their photocatalytic activities. Herein, a well-designed Z-scheme ZnIn₂S₄-S/CNTs/RP (ZIS-S/CNTs/RP) nanocomposite was fabricated according to an energy band alignment steering strategy to realize superior photocatalytic H₂ evolution performance. The ZIS-S/CNTs/RP nanocomposite shows an efficient photocatalytic H₂ evolution rate of 1639.9 μmol g^-1h^-1, which is noticeably higher than that of pristine red phosphorus (RP) and CNTs/RP and ZIS-S/RP composites, as well as those of the compared heterojunctions using bulk RP or ZnIn₂S₄. Owing to the modification of nanosized RP and the introduction of sulfur vacancies in ZnIn₂S₄, a tailored energy band alignment of the heterojunction with a higher reduction potential and larger Fermi level potential difference was achieved, which resulted in significantly increased photogenerated electron-hole separation efficiency and a more efficient Z-scheme charge transfer mechanism, thus promoting the photocatalytic activity of ZIS-S/CNTs/RP. This work aims to provide a novel effective strategy for the construction of high-performance heterojunction photocatalysts by energy band engineering.

3D hollow MXene@ZnIn2S4 heterojunction with rich zinc vacancies for highly efficient visible-light photocatalytic reduction

Well-designed heterojunction semicounductor coupled with high-conductive cocatalyst can obtain boosted photocatalytic activity. Herein, a novel three-dimensional (3D) hollow heterojunction was prepared by coating the indium zinc sulfide (ZnIn₂S₄) nanosheets with rich-zinc vacancies (V_Zn) on 3D hollow titanium carbide (Ti₃C₂). The obtained 3D hollow heterojunction (Ti₃C₂@ZnIn₂S₄) achieved effective optical collection and promoted the separation and transmission of photogenerated carriers as well as the surface reaction of spatial separation. In addition, time-resolved photoluminescence and steady-state photoluminescence spectra indicated that the existence of V_Zn and the introduction of hollow Ti₃C₂ spherical shell effectively inhibited the recombination of photogenerated carriers and accelerated their separation and transmission, thus further enhancing the photocatalytic activity. In addition, the introduction of 3D hollow Ti₃C₂ benefited a larger specific surface area for heavy metal adsorption. Due to the unique structural and compositional characteristics, the heterojunction showed high efficiency of Cr(VI) reduction under visible light. In particular, the optimal Ti₃C₂@ZnIn₂S₄ heterojunction (1%-Ti₃C₂@ZnIn₂S₄) achieved 100% removal of Cr(VI) within 25 min, with a reaction rate constant of 0.225, which was 8.5 times higher than that of the pristine ZnIn₂S₄. The superior reusability and structural stability further indicated the MXene-based novel photocatalyst is promising for application in environmental remediation.

Significantly Raised Visible-Light Photocatalytic H2 Evolution on a 2D/2D ReS2 /In2 ZnS4 van der Waals Heterostructure

Owing to dwindling fossil fuels reserves, the development of alternative renewable energy sources is globally important. Photocatalytic hydrogen (H₂ ) evolution represents a practical and affordable alternative to convert sunlight into carbon-free H₂ fuel. Recently, 2D/2D van der Waals heterostructures (vdWHs) have attracted significant research attention for photocatalysis. Here, for the first time a ReS₂ /In₂ ZnS₄ 2D/2D vdWH synthesized via a facile physical mixing is reported. It exhibits a highly promoted photocatalytic H₂ -evolution rate of 2515 µmol h^-1 g^-1 . Importantly, this exceeds that for pristine In₂ ZnS₄ by about 22.66 times. This, therefore, makes ReS₂ /In₂ ZnS₄ one of the most efficient In₂ ZnS₄ -based photocatalysts without noble-metal cocatalysts. Advanced characterizations and theoretical computations results show that interlayer electronic interaction within ReS₂ /In₂ ZnS₄ vdWH and atomic-level S active centers along the edges of ReS₂ NSs work collaboratively to result in the boosted light-induced H₂ evolution. Results will be of immediate benefit in the rational design and preparation of vdWHs for applications in catalysis/(opto)electronics.

Highly-efficient visible-light-driven photocatalytic H2 evolution integrated with microplastic degradation over MXene/ZnxCd1-xS photocatalyst

The development of highly-efficient photocatalyst for H₂ production integrated with microplastic degradation is significant to meet the demand for clean energy and resolve "white pollution". Herein, a series of MXene/Zn_xCd_1-xS photocatalysts were successfully fabricated for H₂ evolution integrated with degradation of polyethylene terephthalate (PET). The resultant photocatalysts exhibited excellent photocatalytic performance, and the best photocatalytic H₂ evolution rate can reach 14.17 mmol·g^-1·h^-1 in alkaline PET alkaline solution. What's more, the PET was also converted to the useful organic micromolecule, including glycolate, acetate, ethanol, etc. The highly-efficient photocatalytic performance of MXene/Zn_xCd_1-xS photocatalysts can be attributed to the enhanced separation ability of photocarriers and optimum band structure with enhanced oxidation capacity of valence band. Finally, the photocatalytic mechanism was investigated in detail. Overall, this work supplied a new useful guidance for solving the energy problem and microplastic pollution issues, simultaneously.

Highly Dispersive Ni@C and Co@C Nanoparticles Derived from Metal-Organic Monolayers for Enhanced Photocatalytic CO2 Reduction

The metal/carbon composites prepared by direct pyrolysis of metal-organic frameworks (MOFs) are regarded as ideal catalysts. However, conventional MOFs show a three-dimensional bulk structure. For bulk MOF-derived catalysts, most active metal sites are confined in the interior and not fully utilized. In this work, metal-organic monolayers (MOLs) are used as the starting precursors to prepare carbon-wrapped metal nanoparticles, which are further employed as catalysts for photocatalytic CO₂ reduction. The as-prepared Ni-MOLs and Co-MOLs have an ultrathin thickness of ∼1 nm. It is interestingly found that their derived Ni@C and Co@C nanoparticles are highly dispersive and connected with each other like a piece of paper. As compared with bulk MOF-derived counterparts, MOL-derived catalysts increase the accessibility of active metal sites, which can accelerate electron transfer from photosensitizers to Ni@C and Co@C nanoparticles. In this way, the catalytic activity can be greatly improved. Besides, the magnetic nature of Ni@C and Co@C nanoparticles enables the easy separation and recycling of catalysts. It is expected that this work will provide instructive guidelines for the rational design of MOL-derived catalysts.

Surface structure tuning of BiOCl nanosheets by the sequential introduction of oxygen vacancies, PO43- and Ag+ for boosting photodegradation of tetracycline hydrochloride

The surface structure significantly impacts the physicochemical properties of semiconductors. Constructing heterojunction is a universal approach to tune surface structure, which can effectively accelerate the charge transfer at the interface. Here, BiOCl nanosheets which occupy high ratio of surface atoms to entire atoms were used as a model photocatalyst, and a strategy was proposed to tune its surface structure by sequential introduction of oxygen vacancies, PO₄^3- and Ag⁺ on surface of BiOCl nanosheets. In order to inhibit the overgrowth of heterogeneous component, the excess PO₄^3- was timely removed by centrifugation before adding Ag⁺. As a result, the as-obtained optimal sample which was confirmed to be a composite composed of BiOCl, BiPO₄ and AgCl showed superior photocatalytic activity for tetracycline hydrochloride degradation with the rate of 38 times higher than that of pristine BiOCl, which was mainly attributed to the quick migration of photongenerated carrier. The active species h⁺ and •O₂^- played a vital role in this degradation process. Our strategy not only greatly saved investment of noble metal Ag, but also provide superior stability. On the basis of experimental results and density functional theory calculation, the visible-light driven catalytic mechanism was revealed.

Hierarchical fabrication of hollow Co2P nanocages coated with ZnIn2S4 thin layer: Highly efficient noble-metal-free photocatalyst for hydrogen evolution

The directional synthesis of transition metal phosphides was considered to be an effective strategy to solve the overdependence of noble metals on photocatalytic hydrogen evolution (PHE) reactions. Inspiringly, this work reported a facile method for constructing hollow Co₂P nanocages (Co₂P NCGs) that derived from ZIF-67 by calcining and phosphiding procedure in nitrogen atmosphere to act as non-noble metal cocatalysts. Followed with further coating thin-layered ZnIn₂S₄ (ZIS) on the surface of Co₂P NCGs through a hydrothermal reaction, the hierarchical robust Co₂P/ZnIn₂S₄ nanocages (Co₂P/ZIS NCGs) were then delicately fabricated as efficient photocatalysts for PHE reactions. The uniquely hollow structure of Co₂P NCGs largely diffused the photogenerated chargers that induced from ZIS and the closely interfacial contact significantly promoted the separation and transfer of electrons from ZIS to Co₂P according to density functional theory (DFT) calculation, synergistically resulting in an efficient hydrogen generation performance. PHE results showed that an efficient H₂ evolution rate of 7.93 mmol/g/h over 10% Co₂P/ZIS NCGs was achieved, about 10 times higher than that of pristine ZnIn₂S₄. More importantly, the hierarchically hollow Co₂P/ZIS NCGs exhibited ascendant PHE activity in comparison with that of 1% noble metal (Pt, Au, Ag) loaded ZnIn₂S₄ with superior sustainability, all indicating the efficient and stable photocatalysts of Co₂P/ZIS NCGs for PHE reactions.

Few-Layer ZnIn2S4/Laponite Heterostructures: Role of Mg2+ Leaching in Zn Defect Formation

Designing nanostructures with extended light absorption via defect engineering is a useful approach for the synthesis of efficient photocatalysts. Herein, ZnIn₂S₄ was grown hydrothermally in the modified interlayer space of Laponite, resulting in lamellae consisting of Zn-defective ZnIn₂S₄ several unit cells thick. In the process it was found that Mg²⁺ leached from Laponite during synthesis led to the formation of Zn defects in ZnIn₂S₄. This resulted in nanohybrids with light absorption extended across the visible spectrum and in improved charge transfer due to the layered structure formed via confined growth. Compared with pure ZnIn₂S₄, Zn-defective ZnIn₂S₄-Laponite hybrids have increased photocurrent generation and photocatalytic performance. The leaching of Mg²⁺ and the resulting formation of Zn defects was attenuated by addition of 4 mM Mg²⁺ to the reaction, due to a combination of shifting of the equilibrium of Mg²⁺ leaching toward stability, and increased ionic strength. In summary, this work demonstrates the growth of ∼1 nm thick lamellae of ZnIn₂S₄, presents a unique strategy to generate cation defects in nanomaterials and the mechanism behind it, and also provides an approach to mitigate Mg²⁺ leaching in such syntheses.

Molecular-Level Control of the Intersheet Distance and Electronic Coupling between 2D Semiconducting and Metallic Nanosheets: Establishing Design Rules for High-Performance Hybrid Photocatalysts

Hybridization with conductive nanospecies has attracted intense research interest as a general effective means to improve the photocatalytic functionalities of nanostructured materials. To establish universal design rules for high-performance hybrid photocatalysts, correlations between versatile roles of conductive species and interfacial interaction between hybridized species are systematically investigated through fine-control of intersheet distance between photocatalytically active TiO2 and metallic reduced graphene oxide (rGO)/RuO2 nanosheets. Molecular-level tailoring of intersheet distance and electronic coupling between 2D nanosheets can be successfully achieved by restacking of colloidal nanosheet mixture with variable-sized organic intercalants. While the shortest intersheet distance between restacked TiO2 and rGO nanosheets leads to the highest visible-light-driven photocatalytic activity, the best UV-vis photocatalyst performance occurs for moderate intersheet spacing. These results highlight the greater sensitivity of photoinduced electronic excitation to the intersheet distance than that of interfacial charge transfer. The rGO nanosheet can function as effective charge transport pathway and cocatalyst within ≈1.7 nm distance from the semiconducting nanosheet, and as efficient stabilizer for hybridized photocatalyst within ≈1.8 nm. The present study underscores that the intercalative restacking of colloidal nanosheet mixture with intercalants enables molecular-level control of distance between 2D inorganic/graphene nanosheets, which provides a rational design strategy for high-performance hybrid photocatalysts.

Light-Driven Syngas Production over Defective ZnIn2 S4 Nanosheets

Photocatalytic syngas (CO and H₂ ) production with CO₂ as gas source not only ameliorates greenhouse effect, but also produces valuable chemical feedstocks. However, traditional photocatalytic systems require noble metal or suffers from low yield. Here, we demonstrate that S vacancies ZnIn₂ S₄ (V_S -ZnIn₂ S₄ ) nanosheets are an ideal photocatalyst to drive CO₂ reduction into syngas. It is found that building S vacancies can endow ZnIn₂ S₄ with stronger photoabsorption, efficient electron-hole separation, and larger CO₂ adsorption, finally promoting both hydrogen evolution reaction (HER) and CO₂ reduction reaction (CO₂ RR). The syngas yield of CO and H₂ is therefore significantly increased. In contrast to pristine ZnIn₂ S₄ , the syngas yield over V_S -ZnIn₂ S₄ can be improved by roughly ≈4.73 times and the CO/H₂ ratio is modified from 1:4.18 to 1:1. Total amount of syngas after 12 h photocatalysis is as high as 63.20 mmol g^-1 without use of any noble metals, which is even higher than those of traditional noble metal-based catalysts in the reported literatures. This work demonstrates the critical role of S vacancies in mediating catalytic activity and selectivity, and highlights the attractive ability of defective ZnIn₂ S₄ for light-driven syngas production.

Atomic Sandwiched p-n Homojunctions

Semiconductor p-n junctions have been explored and applied in photoelectrochemical (PEC) water splitting, but serious carrier recombination and sluggish oxygen evolution reaction (OER) dynamics have demanded further progress in p-n junction photoelectrode design. Here, via a controllable NH₃ treatment, we construct sandwiched p-n homojunctions in three-unit-cells n-type SnS₂ (n-SnS₂ ) nanosheet arrays using nitrogen (N) as acceptor dopants. The optimal N-doped n-SnS₂ (pnp-SnS₂ ) with such unique structure achieves a record photocurrent density of 3.28 mA cm^-2 , which is 21 times as high as that of n-SnS₂ and the highest value among all the SnS₂ photoanodes reported so far. Moreover, the stoichiometric O₂ and H₂ evolution from water was achieved with Faradaic efficiencies close to 100 %. The superior performance could be attributed to the facilitated electron-hole separation/transfer, accelerated surface OER kinetics, prolonged carrier lifetime, and improved structural stability.

Mechanism of surface and interface engineering under diverse dimensional combinations: the construction of efficient nanostructured MXene-based photocatalysts

Proposed scheme of the surface and interface engineering to improve the charge separation efficiency of MXene-based photocatalysts.

Ultrafast synthesis of near-zero-cost S-doped Ni(OH)2 on C3N5 under ambient conditions with enhanced photocatalytic activity

2D S–Ni(OH)2 is facially planted on 2D C3N5 at room temperature in 30 minutes via a reaction between Ni(NO3)2 and Na2S in aqueous solution. Due to quick internal charge transfer efficiency, the hybrid is highly efficient for photocatalytic H2 production.

Atomic-Level and Modulated Interfaces of Photocatalyst Heterostructure Constructed by External Defect-Induced Strategy: A Critical Review

Despite the existence of numerous photocatalyst heterostructures, their separation efficiency and charge flow precision remain low due to the poor study on interfacial properties. The photocatalysts with confined defects can effectively control the photogenerated carrier migration, but the metastability of such defects considerably decreases the photocatalyst stability. Meanwhile, the introduction of defective region can increase the coordinative unsaturation and delocalize local electrons to promote their interactions with the molecules/ions in that region. The selective growth of modulated heterogeneous interface by defect-induced strategy may not only increase the stability of defective structures, but also enhance the migration of interfacial charges. Using this method, photocatalytic heterostructures with low contact resistances and intimate interfaces are constructed to achieve the optimal charge migration in terms of efficiency and accuracy. In this work, the point, linear, and planar heterogeneous interfaces and related defect engineering techniques are discussed. Particularly, it is focused on the external, defect-induced interfacial heterogeneities with various spatial and dimensional configurations, which exhibit modulated and controllable interfacial properties. Furthermore, the main aspects of fabricating photocatalyst heterostructures by the defect-induced strategy, including the i) controllable generation of defects, ii) advanced characterization methods, and iii) elaborate construction of the minimal interface, are described.

Constructing a 2D/2D heterojunction of MoSe2/ZnIn2S4 nanosheets for enhanced photocatalytic hydrogen evolution

2D/2D MoSe₂/ZnIn₂S₄ heterojunctions exhibit high photocatalytic activity owing to MoSe₂ as a cocatalyst, which provides more active sites, reducing the overpotential and the activation energy for water reduction.

Direct Z-scheme CdS–NiPc heterojunctions as noble metal-free photocatalysts for enhanced photocatalytic hydrogen evolution

A direct Z-scheme CdS-NiPc heterojunction was successfully synthesized by a one-step hydrothermal method. The optimal photocatalytic H2 production rate could reach 17.74 mmol h−1 g−1, which was 19.1 times higher than that of the pure CdS sample.

Hollow core–shell Co9S8@In2S3 nanotube heterojunctions toward optimized photothermal–photocatalytic performance

Hollow core–shell Co9S8@In2S3 photocatalysts show excellent photothermal–photocatalytic hydrogen evolution, which is attributed to unique hollow structure, the successfully constructed heterojunction and core–shell nanostructure.