Photocatalytic Water Splitting Research Articles

Quasi-One-Dimensional Zigzag Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution from Water.

Covalent organic frameworks (COFs) have potential applications in a wide range of fields. However, it remains a critical challenge to constrain their covalent expansions in the one-dimensional (1D) direction. Here, we developed a general approach to fabricate 15 different highly crystalline COFs with zigzag-packed 1D porous organic chains through the condensation of V-shaped ditopic linkers and X-shaped tetratopic knots. Appropriate geometrical combinations of a wide scope of linkers and knots with distinct aromatic cores, linkages, and functionalities offer a series of quasi-1D COFs with dominant pore sizes of 7-13 Å and surface areas of 116-784 m2 g-1. Among them, nitrogen (N)-doped 1D COFs with site-specific doping of heteroatoms favor a tunable control of band structures and conjugations and thus allow a remarkable hydrogen evolution rate up to 80 mmol g-1 h-1 in photocatalytic water splitting. This general strategy toward programming function in porous crystalline materials has the potential to tune the topologically well-defined electronic properties through precisely periodic doping.

Theoretical-level insights on the molecular structures and LiCl dopant of carbon nitride single crystals for solar-driven overall water splitting

Addressing energy and environmental challenges requires sustainable technologies like photocatalytic overall water splitting (OWS) using graphitic carbon nitride (GCN). This study investigates the molecular structures and LiCl doping effects in GCN variants-poly(triazine imide) intercalated with LiCl (PTI/Li+Cl-), and heptazine-based crystalline GCN (HCCN)-to understand their suitability for OWS. Experimental results show that PTI/Li+Cl- exhibits superior OWS activity, producing 802.3 μmol h-1 gcat-1 of H₂ and 395.6 μmol h-1 gcat-1 of O₂, due to its active planes and favorable electron transfer. In contrast, HCCN shows high H₂ production but no O₂ release. Density functional theory calculations reveal that triazine structures are more favorable for oxygen evolution reaction (OER) while heptazine structures excel in hydrogen evolution reaction (HER). LiCl doping can enhance OWS performance by improving electronic conductivity and reducing reaction activation energy. The results encourage the combination of triazine and heptazine structures with LiCl doping to optimize OWS, offering a theoretical basis for designing efficient GCN-based photocatalysts.

Arsenene/Ti2CO2 Heterojunction as a Promising Z‐Scheme Photocatalyst for Overall Water Splitting

AbstractIn order to address imminent energy and environmental challenges, photocatalytic water splitting emerges as a promising way for harnessing solar radiation to generate clean chemical energy. 2D arsenene (β‐As) has notable catalytic activity in hydrogen production. Based on first principles calculations and non‐adiabatic molecular dynamics (NAMD) simulations, the β‐As/Ti2CO2 heterojunction is predicted to be a promising Z‐scheme photocatalyst for overall solar water splitting. It has a desirable energy band structure with the valence band maximum of Ti2CO2 and the conduction band minimum of β‐As well below and above the redox potentials of H2O. Both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can proceed spontaneously under light irradiation. NAMD simulations confirm that it is a Z‐scheme photocatalyst with fast electron–hole combination dynamics. Instead of by intrinsic electric field, such a fast electron–hole combination is driven by a large nonadiabatic coupling. The heterojunction exhibits strong optical absorption in the visible and ultraviolet regions. The estimated solar‐to‐hydrogen (STH) efficiency limit of β‐As/Ti2CO2 reaches 32%, which is the highest among all β‐As based junctions reported in the literature. These results suggest that β‐As/Ti2CO2 is a promising photocatalyst for achieving overall water splitting.

Construction of a Z-scheme heterojunction based on two-dimensional Janus materials XWSiN2 (X=S; Se; Te) for effective photocatalytic water splitting by DFT

Photocatalysts play an important role in solving energy problems, and Z-scheme heterojunctions have garnered significant interest due to their ability to efficiently separate photogenerated carriers and improve redox capacity. In this work, we construct a Z-scheme heterojunction by substituting Se and Te for S atoms in the SWSiN2 bilayer. The findings demonstrate that they have high kinetic stability, and the construction of heterojunctions can narrow the bandgap, effectively improving light absorption. The existence of the built-in electric field can be explained by studying the charge density difference, which breaks through the band gap limitation in water photocatalytic splitting. Their photocatalytic characteristics with and without strain are described in depth, with the spectroscopic limited maximum efficiency (SLME) of TeWSiN2/SWSiN2 surpassing 30 % under no strain. With tensile strain, SeWSiN2/SWSiN2 energy bands rise, but TeWSiN2/SWSiN2 energy bands decrease. Meanwhile, the band edge arrangement of XWSiN2/SWSiN2 (X=Se; Te) becomes smaller with increasing strain. The spectral finite maximum efficiency of SeWSiN2/SWSiN2 increases from 12 % to 27 % and shows good light absorption (ηSTH = 10.60 % for SeWSiN2/SWSiN2, ηSTH = 14.17 % for TeWSiN2/SWSiN2) and carrier utilization.

Optimizing junction interface integrity between 3D/2D defect pyrochlore Bi1.8Fe0.2WO6 and g-C3N4 nanostructures: A novel multifunctional nanocomposite for enhanced photocatalytic and photo-electrocatalytic water splitting and water remediation applications

In this work, a simplistic composite fabrication of defect pyrochlore Bi1.8Fe0.2WO6 (BFWO) and g-C3N4 (g-CN) was carried out to augment the photocatalytic degradation kinetics and Hydrogen (H2) evolution rate. The structural confirmation through XRD and FTIR confirmed the successful formation of pristine g-C3N4, BFWO NPs, and their composites. FESEM micrographs revealed multilayered sheet-like formation for C3N4 whereas irregular cuboid-shaped structure for BFWO NPs. In the composite formation, the sheets tended to appear wrapped around the BFWO NPs. The UV-DRS absorbance spectra exhibited a highlighted increase in the absorbance region towards the visible light region following a decrease in the band gap. The photoluminescence lifetime studies revealed an enhanced lifetime of excitons to 6.21 ns for 50:50 (g-C3N4: BFWO) composite formation, whereas pristine g-CN displayed an average lifetime of about 4.79 ns. The degradation efficacy in the removal of RhB and MB from water revealed up to 100% and 95.5% removal rates in under 90 mins and 180 mins respectively using the 50:50 composite formation. Similarly, the H2 evolution rate was significantly improved and exhibited up to 370 μmol/h/g. The photo-electrochemical studies revealed a sharp charge separation of excitons for 50:50 (g-C3N4: BFWO) with a maximum photocurrent density of -0.54 μA/cm2 @ 0 V which is 3.6 times and 13.5 times higher than bare g-CN and BFWO. 1.33 V vs. RHE for OER kinetics and -0.09 V vs RHE for HER kinetics were the minimal onset potential exhibited for equal ratios of BFWO and g-CN. Coupled with the heightened charge separation, reduced recombination rate, and optimal band edge positions, the photocatalytic efficiency in the degradation of RhB and MB and water-splitting reactions were improved.

Single-Particle Imaging Photoinduced Charge Transfer of Ferroelectric Polarized Heterostructures for Photocatalysis.

Piezoelectric-assisted photocatalysis has a huge potential in solving the energy shortage and environmental pollution problems, and imaging their detailed charge-transfer process can provide in-depth understanding for the development of high-active piezo-photocatalysts; however, it is still challenging. Herein, topotactic heterostructures of TiO2@BaTiO3 (TO@BTO-S) were constructed by the epitaxial growth of ferroelectric BaTiO3 mesocrystals on TiO2-{001} facets, resulting in a ferroelectric photocatalyst with a polarization orientation on the surface. Notably, the photoinduced charge transfer in ferroelectric TiO2@BaTiO3 was accurately monitored and directly visualized at the single-particle level by the advanced photoluminescence (PL) imaging microscopy systems. The longer PL lifetime of TO@BTO-S demonstrated the efficient charge separation caused by a built-in electric field, which is constructed by the polarization orientation of BaTiO3 mesocrystals. Therefore, the TO@BTO-S heterostructure exhibits efficient piezoelectric-assisted photocatalytic pure water splitting, which is 290 times higher than photocatalysis. This work revealed time/spatial-resolved photoinduced charge transfer in piezoelectric assistance photocatalysts at the single-particle level and demonstrated the great role of polarization orientation in promoting charge transfer for photocatalysis.

In-situ construction of N-doped Zn0.6Cd0.4S/oxygen vacancy-rich WO3 Z-scheme heterojunction compound for boosting photocatalytic hydrogen production

Photocatalytic water splitting technology for H2 production represents a promising and sustainable approach to clean energy generation. In this study, a high concentration of oxygen vacancies was introduced into tungsten trioxide (WO3) to create a vacancy-rich layer. This modified WO3 (WO3-x) was then combined with N-doped Zn0.6Cd0.4S through a hydrothermal synthesis, resulting in the formation of a Z-scheme heterojunction composite aimed at enhancing photocatalytic performance. Under visible light, the H2 production activity of the composite reached an impressive 8.52 mmol·g−1 without adding co-catalyst Pt. This corresponds to enhancements of 7.82 and 4.39 times the production yield of pure ZCS and ZCSN, respectively. However, the hydrogen production increased to 21.98 mmol·g−1 when Pt was added as a co-catalyst. Furthermore, an array of characterizations were employed to elucidate the presence of oxygen vacancies and the establishment of the Z-scheme heterojunction. This structural enhancement significantly facilitates the utilization of photo-generated electrons while effectively preventing photo-corrosion of ZCSN, thus improving material stability. Our study provides a new scheme for the incorporation of oxygen-rich vacancy and the construction of Z-scheme heterojunction, demonstrating a synergistic effect that greatly advances photocatalytic performance.

Two-dimensional ferroelastic semiconductors InXY (X = S, Se; Y = Cl, Br, I): Promising candidates for photocatalytic water splitting with tunable electronic anisotropy

We have identified a class of two-dimensional ferroelastic monolayers, denoted as InXY (where X = S, Se; Y = Cl, Br, I), through first-principles calculations. The dynamic, thermal, and mechanical stabilities of these InXY monolayers are validated by phonon dispersion spectra, AIMD calculations, and elastic constants, respectively. These monolayers exhibit semiconducting behavior with bandgaps ranging from 1.94 to 2.85 eV and possess excellent ferroelasticity with strong ferroelastic signals and moderate ferroelastic switching barriers. Notably, the band edge positions of InSBr and InSI monolayers are observed to stride the water redox potentials at pH = 0, indicating their potential as photocatalysts for water splitting in acidic environments. We also explored the effects of biaxial strain on the band edge alignments and photocatalytic performance of these monolayers. Moreover, the InXY monolayers exhibit excellent anisotropic optical absorption across the visible to ultraviolet regions, along with high anisotropic carrier transport. The coupling of ferroelastic and anisotropic properties in these monolayers offers promising opportunities for designing controllable electronic devices, thereby expanding their potential applications in multifunctional materials. Our findings reveal that the InXY monolayers are promising candidates for efficient photocatalytic water splitting and controllable optoelectronic applications.

Cd0.9Zn0.1S/NiB Schottky heterojunction for efficient photothermal-assisted photocatalytic hydrogen evolution

Within the theoretical framework of computational prediction, this study introduces a novel tetrapodal Cd0.9Zn0.1S/NiB (CZS/NiB) Schottky heterojunction material, which demonstrates exceptional photothermal effects and remarkable photocatalytic properties. Notably, under visible light irradiation for 3 h, the photocatalytic hydrogen evolution activity of CZS/NiB-3 % surpasses that of pure CZS by a factor of 10.52. This outstanding photocatalytic hydrogen production performance stems from the successful construction of the CZS/NiB-3 % Schottky heterojunction with promoted the separation and transfer of photogenerated charge carriers and excellent photothermal effect. Additionally, the synthesized CZS/NiB exhibits high photostability and cycling stability. The favorable photothermal effect of the synthesized photocatalyst was experimentally validated through infrared thermography technology. Through in-depth computational investigations using density functional theory, the pathways of charge transfer in the Schottky heterojunction are validated. This study provides a feasible strategy for research on photocatalytic water splitting for hydrogen evolution.

Aqueous glass-coated CsPbI3 quantum dots implanted in g-C3N4 nanosheets for efficient photocatalytic water splitting and H2O2 generation

Increasing visible light harvesting and improving charge carrier separation and transfer efficiency are crucial for photocatalytic H2O2 generation using graphitic carbon nitrides (g-C3N4) based catalysts. In this paper, a high temperature solid synthesis was developed to create water stable SiO2 glass coated CsPbI3 (CsPbI3@SiO2) quantum dots (QDs) with high brightness and extraordinary stability. These CsPbI3@SiO2 QDs were implanted in superior thin g-C3N4 nanosheets via a solvothermal synthesis. The red-emission of CsPbI3 QDs and the blue emission of g-C3N4 nanosheets were quenched after incorporation to confirm that photogenerated electron transition occurred. The further polymerization of g-C3N4 during solvothermal treatment resulted in CsPbI3@SiO2/g-C3N4 with well-developed interface to improve the charge transfer efficiency. A type II heterostructure formed after CsPbI3@SiO2 QDs incorporated with g-C3N4 nanosheets. The heterostructure revealed enhanced photocatalytic H2 and H2O2 generation, in which the evolution rate of H2O2 was 2454.4 μmol·g−1·h−1 while the photocatalytic H2 generation rate was 2463.1 μmol·g−1·h−1. The mechanism test indicated that the photocatalytic production of H2O2 was carried through a two-step single-electron redox process. Superoxide radicals were important intermediates for the generation of H2O2. This study provides a new scheme for the preparation of g-C3N4 based heterojunction photocatalyst for efficient photocatalytic production of H2O2 and H2.

Solvated Electrons Generated on the Surface of Na-SPHI for Boosting Visible Light Photocatalytic Hydrogen Evolution with Ultra-High AQE.

Enhancing the utilization of visible-light-active semiconductors with an excellent apparent quantum efficiency (AQE) remains a significant and challenging goal in the realm of photocatalytic water splitting. In this study, a fully condensed sulfur-doped poly(heptazine imide) metalized with Na (Na-SPHI) is synthesized by an ionothermal method by using eutectic NaCl/LiCl mixture as the ionic solvent. Comprehensive characterizations of the obtained Na-SPHI reveal several advantageous features, including heightened light absorption, facilitated exciton dissociation, and expedited charge transfer. More importantly, solvated electron, powerful reducing agents, can be generated on the surface of Na-SPHI upon irradiation with visible light. Benefiting from above advantage, the Na-SPHI exhibits an excellent H2 evolution rate of 571.8 µmol·h-1 under visible light illumination and a super-high AQE of 61.7% at 420nm. This research emphasizes the significance of the solvated electron on the surface of photocatalyst in overcoming the challenges associated with visible light-driven photocatalysis, showcasing its potential application in photocatalytic water splitting.

Two-dimensional MoSTe/MSi2N4 (M = Mo, W) van der Waals heterojunctions for photocatalytic water-splitting: A first-principles study

Direct Z-scheme heterojunction is a promising candidate for photocatalysts because it effectively separates the photogenerated electrons-hole pairs with strong redox capacity. In this paper, the MoSTe-MSi2N4 (M = Mo, W) heterostructures are constructed, and their stability, electronic structures and photocatalytic performance are investigated. The results demonstrate that the absorption properties of heterojunctions are significantly better than that of monolayers in both visible and ultraviolet light regions. Expressly, heterojunctions have the direct Z-scheme charge transfer mechanism when S surface of MoSTe contacted with MSi2N4 (namely S-M). Further calculation find that the S-M heterojunctions can perform stable photocatalytic water splitting in both acidic and neutral environments, and have better hydrogen evolution reaction. These theoretical predictions suggest that the MoSTe-MSi2N4 heterostructures are high-performance photocatalysts for the preparation of hydrogen gas.

Direct Z-scheme ZrS2/InP heterostructure as an efficient photocatalyst for overall water-splitting under acidic, alkaline and neutral environments

Photocatalytic water-splitting for hydrogen production by building heterostructure is an efficient approach to resolve the current environmental pollution problem. Here, the ZrS2/InP heterostructure with a direct Z-scheme have been constructed, and the first-principles calculations with Heyd-Scuseria-Ernzerhof (HSE06) hybrid function and density functional dispersion correction (DFT-D3) have been used to study their structural stabilities, electronic properties, photocatalytic mechanisms and optical features. The findings reveal that the ZrS2/InP heterostructure is a direct bandgap semiconductor having a type-II energy band alignment, where electrons mobilize from InP to ZrS2 monolayer at the interface of the heterostructure, leading to the creation of a build-in electric field pointing from InP to ZrS2. The ZrS2/InP heterostructure is competent for photocatalytic water-splitting owing to its advantageous band edge positions. In addition, the ZrS2/InP heterostructure possesses superior visible light absorption properties than the two monolayers structures, with a solar-to-hydrogen (STH) efficiency of 7.11 % and useable in acidic, alkaline and neutral environments. These excellent properties enable ZrS2/InP heterostructure to be an efficient photocatalyst for overall water-splitting. This effort not only proves the possibility of applying heterostructure in photocatalytic water-splitting but also has important implications for designing efficient direct Z-scheme photocatalysts.

Copper/ cerium metal organic frame work as highly efficient structures for solar power-induced hydrogen generation through the process of water splitting

Increased dependence on fossil fuels as energy sources strongly contributes in both global warming and environmental pollution, leading to serious impacts on human-beings and societies. Therefore, shift from hydrocarbon-based energy to alternative green, sustainable and renewable sources of energy has been globally stimulated in past decades. In an agreement with this context, hydrogen is counted as one of these sources which has been paid strong attention recently due to its high energy content and no harmful emissions. Consequently, this study introduces production of clean green hydrogen through the process of photocatalytic water splitting which is a cost-effective route and releases zero emissions. A series of copper/ or cerium based metal–organic frameworks were successfully prepared via one-pot solvothermal technique and were presented as three novel photocatalysts for hydrogen production from water. The photocatalytic performances of these structures were investigated under visible light irradiation, revealing the highest activity for copper doped cerium metal–organic framework. It exhibited a maximum pure hydrogen productivity of 465 mmol per hour/ gram which was much higher than those the detected productivity by copper and cerium metal–organic frameworks (289 and 375 mmol per hour/ gram respectively). Heterojunction between the two central metals as well as effective charge separation in copper doped cerium metal–organic framework are reasons of its superiority in hydrogen evolution exploit, compared to the other two structures. The recyclability of copper doped cerium metal–organic framework demonstrated high reliability since it showed nearly stable yields of hydrogen over ten cycles of photocatalytic reuse. Therefore, the presented binary metals organic framework establishes new platform for photocatalysts in process of hydrogen production through water splitting.

Synergistic effect of oxygen vacancies and functionalized ligands selectively enhanced the photocatalytic oxidation of methane to carbon monoxide

The titanium-based metal–organic framework MIL-125(Ti) has been widely investigated in photocatalytic carbon dioxide reduction and water splitting, but rarely studied in photocatalytic methane conversion by employing only water as an oxidant under mild conditions. Simultaneously controlling products with high yield and selectivity is highly challenging in methane conversion. Herein, we develop a series of functionalized titanium metal–organic frameworks via a facile organic ligand exchange process. The abundant Ti3+ active sites induced by oxygen vacancies and functionalized ligands synergistically facilitate the adsorption and activation of methane molecules. The carbon monoxide yield over NH2-MIL-125(Ti) increased to 198.6 μmol·gcat−1·h−1 with a high selectivity of 87.1 % under simulated solar illumination. Combined with in-situ characterizations and density functional theoretical calculations, the results confirmed that Ti3+ active sites induced by oxygen vacancies and amino functional groups synergistically enhanced the photocatalytic conversion of methane and elucidate CH4-to-CO conversion mechanism. This study does not only provide insights into the rational design of metal–organic frameworks with copious oxygen vacancies and functional groups, but also provides some significant cognition for photocatalytic methane conversion.

Direct Z-scheme GeC/GaSe heterojunction by first-principles study for photocatalytic water splitting

In this study, we constructed the direct Z-scheme heterojunction by vertically stacking monolayers of GeC and GaSe. And systematically explored its stability, electronic structure, optical absorption characteristics and photocatalytic mechanism with first principles calculations. Our results show that the GeC/GaSe heterojunction possesses an indirect-gap of 1.88 eV and exhibits a staggered energy-band structure. In comparison to the individual monolayers of GeC and GaSe, the GeC/GaSe heterojunction has more excellent absorption of far-ultraviolet and visible light. And the electrons and holes in the GeC/GaSe heterojunction have a transmission path resembling the letter Z. There is also an internal electric field from GeC to GaSe in the heterojunction, which accelerates the photoelectrons and holes along the Z direction when the heterojunction receives light. Furthermore, further studies suggest that the GeC/GaSe heterojunction can be utilized as a photocatalytic material for water splitting under pH = 0–14. Besides, the bandwidth and optical absorption properties of the GeC/GaSe heterojunction can be adjusted by biaxial strains. Moreover, Gibbs free energy calculations during water splitting demonstrate that the GeC/GaSe heterojunction exhibits a highly driven force for both OER and HER. Thus, direct Z-scheme GeC/GaSe heterojunction has the capability to be a promising photocatalyst for water splitting.

Innovative Type-II ZnSe/InSSe heterojunction: Photocatalytic properties and strain modulation from first-principles calculations

In this study, we propose an innovative type-II ZnSe/InSSe heterojunction for efficient photocatalytic water-splitting. This heterojunction exhibits a direct band gap of 1.9 eV and staggered band alignment, which efficiently separates photogenerated carriers, facilitating overall water-splitting. The built-in electric field drives electrons to accumulate in the InSSe layer and holes accumulate in the ZnSe layer, thereby suppressing recombination and enhancing photocatalytic efficiency. The solar-to-hydrogen efficiency reaches 8.92 %. Furthermore, the electronic and optical properties of ZnSe/InSSe heterojunction can be modified by biaxial strain, with tensile strain significantly improving visible light absorption and overall efficiency. Under tensile strain, the band gap decreases, enhancing the light absorption capability in the visible range, which further boosts the photocatalytic performance. Our findings demonstrate the ZnSe/InSSe heterojunction as a promising candidate for high-efficiency photocatalytic hydrogen production, offering valuable insights for future photocatalyst development. This research provides a potential pathway to optimize semiconductor heterojunctions for sustainable energy applications through strain engineering.

Performance of photocatalytic water splitting for hydrogen production using kelp as a sacrificial agent

The study investigated the influence of catalyst concentration, co-catalyst loading ratio, sacrificial agent concentration, irradiation time, irradiation intensity and different pretreatments of sacrificial agent on hydrogen production, using multistage porous Pd/TiO2 as the catalyst and kelp as the sacrificial agent. The morphological and structural changes in the catalyst, sacrificial agent, and their mixtures before and after the photocatalysis were analyzed using Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) spectroscopy. Based upon single-factor experiments, it was confirmed that mannitol was the primary substance acting as a sacrificial agent in kelp. Orthogonal experiments were conducted to determine the optimum conditions for hydrogen production with a reaction liquid volume of 100 mL. The highest hydrogen production efficiency was achieved for the following conditions: kelp sacrificial agent's concentration of 1.5 g/L; concentration of multistage porous Pd/TiO2 catalyst of 3.5 g/L; Pd loading ratio of 1 wt%. Under these conditions, hydrogen production reached the value of 121.1 μmol in 4 h. Under the same conditions, replacing the kelp sacrificial agent with kelp treated with 4% alkali, resulted in a corresponding hydrogen production of 141.0 μmol in 4 h. Compared to other common biomass sacrificial agents, the use of kelp as a sacrificial agent for photocatalytic water splitting demonstrates superior hydrogen production performance.

Recent research progress of MOFs-based heterostructures for photocatalytic hydrogen evolution

The growing serious energy crisis and environmental pollution expedite the development of green hydrogen energy. Photocatalytic water splitting technology, converting solar energy into chemical energy directly, provides a clean and economical way for hydrogen evolution. For the past few years, metal–organic frameworks (MOFs) semiconductor materials have become a research hotspot in the field of photocatalytic hydrogen evolution (PHE) due to their multiple advantages, including adjustable structure, high porosity, large specific surface area, abundant active sites, and so forth. Besides this, the construction of heterogeneous structures based on MOFs materials can further improve PHE performance through the effective internal electric field directional transfer of photogenerated electrons and the superior utilization rate of sunlight in comparison to the single MOFs photocatalyst. Herein, in this minireview, we summed up the varieties of synthesis methods of diverse types of MOFs heterojunction complex materials, discussed the H2 evolution efficiency based on this heterostructure photocatalyst in detail, and lastly proposed the advantages, limitations, and outlook of MOFs composites in the PHE field. We sincerely hope this review can provide a reference for future research based on MOFs materials for alleviating the current energy crisis.

Manipulate photocatalytic overall water splitting performance of the Sc2CCl2/SiSe heterostructure by S impurity: Insight from Gibbs free energy and carrier nonadiabatic dynamics

Numerous photocatalytic hydrogen and oxygen evolution reactions (HER and OER) with heterostructures are reported but have no practicality because the less sophisticated heterostructures have no enough driving force to overcome the Gibbs free energy necessary for the spontaneous proceed of these reactions. Here, we demonstrate that these reactions with the Sc2CCl2/SiSe heterostructure can be manipulated to spontaneously proceed by S atom impurity. Based on the electronic properties by the first-principles calculations, the direct Z-scheme of the photocatalytic HER and OER with the Sc2CCl2/SiSe and S-doped Sc2CCl2/SiSe heterostructures are constructed. The calculated Gibbs free energies confirm that OER cannot spontaneously proceed with Sc2CCl2/SiSe heterostructure but can proceed with the S-doped Sc2CCl2/SiSe heterostructures, and HER can spontaneously proceed with all heterostructures. The maximum solar-to-hydrogen efficiencies of the latter can reach 11.48 %, indicating that the photocatalytic performance is maintained. Moreover, the nonadiabatic molecular dynamics results reveal the prolonged lifetimes of the photogenerated carriers, indicating the redox ability is well protected. Therefore, the S atom impurity enables the Sc2CCl2/SiSe heterostructure to be a promising candidate for developing catalysts for photocatalytic overall water splitting.