Facile layer-by-layer self-assembly of 2D perovskite niobate and layered double hydroxide nanosheets for enhanced photocatalytic oxygen generation

Photocatalytic O₂-generation reaction is recognized as a crucial step in water splitting and has drawn great attention of researchers. In this work, a hetero-layered composite photocatalyst was successfully prepared by a facile self-assembly method based on electrostatic interaction between oppositely charged Zn/Cr-layered double hydroxide (Zn/Cr-LDH) and lead niobate nanosheets. The layer-by-layer stacking of Zn/Cr-LDH and HPb₂Nb₃O₁₀ nanosheets was beneficial for rapid migration of photo-induced charge carriers inside the photocatalyst because of large contact area. In the meantime, Zn/Cr-LDH and HPb₂Nb₃O₁₀ components exhibited suitable energy-band alignment, which led to efficient separation of photo-induced charge carriers. The composite photocatalyst showed enhanced photocatalytic O₂-generation activity under visible-light irradiation without loading cocatalyst. Briefly, this work expanded the applications of AB₂Nb₃O₁₀-based materials in photocatalytic energy conversion and proved that constructing composites based on electrostatic self-assembly of complementary 2D materials is a promising strategy for development of more efficient photocatalysts.     

A critical review in strategies to improve photocatalytic water splitting towards hydrogen production

Water splitting for hydrogen production under light irradiation is an ideal system to provide renewable energy sources and to reduce global warming effects. Even though significant efforts have been devoted to fabricate advanced nanocomposite materials, the main challenge persists, which is lower efficiency and selectivity towards H₂ evolution under solar energy. In this review, recent developments in photo-catalysts, fabrication of novel heterojunction constructions and factors influencing the photocatalytic process for dynamic H₂ production have been discussed. In the mainstream, recent developments in TiO₂ and g-C₃N₄ based photo-catalysts and their potential for H₂ production are extensively studied. The improvements have been classified as strategies to improve different factors of photocatalytic water splitting such as Z-scheme systems and influence of operating parameters such as band gap, morphology, temperature, light intensity, oxygen vacancies, pH, and sacrificial reagents. Moreover, thermodynamics for selective photocatalytic H₂ production are critically discussed. The advances in photo-reactors and their role to provide more light distribution and surface area contact between catalyst and light were systematically described. By applying the optimum operating parameters and new engineering approach on photoreactor, the efficiency of semiconductor photocatalysts for H₂ production can be enhanced. The future research and perspectives for photocatalytic water splitting were also suggested.     

ZnCr LDH nanosheets modified graphitic carbon nitride for enhanced photocatalytic hydrogen production

ZnCr layered double hydroxides (ZnCr LDH) nanosheets modified graphitic carbon nitride (g-C₃N₄) nanohybrids were fabricated via a self-assembly procedure through electrostatic interaction between these two components. Such 2D-2D inorganic-organic hybrid material was employed for photocatalytic hydrogen production under visible light for the first time. The physical and photophysical properties of the hybrid nanocomposites were investigated to reveal the effect of ZnCr LDH nanosheets on the photocatalytic activities of g-C₃N₄. It was found that 1 wt% ZnCr LDH nanosheets modified g-C₃N₄ was optimal for the formation of intimate interfacial contact. The visible light photocatalytic H₂ production activity over g-C₃N₄ was enhanced about 2.8 times after ZnCr LDH nanosheets modification. The significant enhancement in photocatalytic performance for ZnCr LDH/g-C₃N₄ heterojunction should be attributed to the promoted charge transfer and separation efficiency, resulting from the intimate interfacial contact and Type II band alignment between ZnCr LDH and g-C₃N₄.     

Preparation of a novel Pd/layered double hydroxide composite membrane for hydrogen filtration and characterization by thermal cycling

A layered double hydroxide (LDH) layer was grown directly on a porous stainless steel (PSS) surface to reduce the pore opening of the PSS and to be a middle layer retarding Pd/Fe interdiffusion. A thin Pd film (∼7.85 μm) was plated on the modified PSS tube by an electroless plating method. A helium leak test proved that the thin Pd on the LDH-modified PSS substrate was free of defects. The membrane had a H₂ flux of 28–36 m³/(m² h) and H₂/He selectivity larger than 2000 at a pressure difference of 1 bar. Thermal cycling between room temperature and 673 K was performed and showed that the membrane exhibited good permeance and selectivity. Long-term evaluation (1500 h) of the membrane at 673 K showed static results of H₂ flux (∼30 m³/(m² h)) and H₂/He selectivity (∼2000) over the 1500 h test period.     

Phosphorylation of NiAl-layered double hydroxide nanosheets as a novel cocatalyst for photocatalytic hydrogen evolution

In previous studies, it has been shown that phosphorus and phosphate can improve the conductivity, change the electronic structure, and accept electrons from catalysts. In this study, we obtained phosphorylated NiAl-layered double hydroxide (P-LDH) nanosheets and used them as a novel cocatalyst in photocatalytic hydrogen evolution. After assembly with g-C₃N₄ via an in situ process, these noble-metal-free composite photocatalysts showed superior photocatalytic hydrogen evolution activity. It was also found that the efficiency of H₂ production on the optimal composite was 1.5 times that of Pt-modified g-C₃N₄. Characterization of the photocatalysts revealed that the effects of P-LDH were different from those of other bimetallic LDHs, showing a lower overpotential and faster reaction kinetics of H₂ evolution. Moreover, it was found that P-LDH has a higher surface work function than that of g-C₃N₄, leading to the formation of an interfacial electric field from CN toward P-LDH. Therefore, modifying P-LDH can efficiently improve the interfacial charge transfer rate, suppress photogenerated charge recombination, and lower the surface overpotential of g-C₃N₄. This study serves as guidance on the design of more effective cocatalysts for photocatalytic hydrogen evolution reactions.     

Recent advances in covalent organic framework (COF) nanotextures with band engineering for stimulating solar hydrogen production: A comprehensive review

Due to the continuous consumption of fossil fuels, natural reserves are depleting and it has been earnest need for developing new sources of energy. Among the several solar energy conversion techniques, photocatalytic hydrogen (H₂) generation is regarded as one of the most promising routes. Till date, several metal-based semiconductor materials have been investigated, however, H₂ generation is not substantial with the notion of sustainable development. Current research trends show the growing interest in advanced and metal free photocatalyst materials such as covalent organic frameworks (COFs) due to their several benefits such as crystalline porous polymers with pre-designed architectures, large surface area, exceptional stability, and ease of molecular functionalization. By combining COFs with other functional materials, composites may be created that display unique characteristics that exceed those of the separate components. This work provides a comprehensive development on COFs as a photocatalysts and their composites/hybrids for photocatalytic hydrogen generation with a focus on visible-light irradiation. To reduce the dependency on novel metals and overcome the drawbacks of individual material, the creation of composite materials based on covalent-organic frameworks (COFs) are systematically discussed. In addition, advantages in terms of performance, stability, durability of composites/hybrids COFs for photocatalytic hydrogen production in reference to traditional catalysts are investigated. Different composites such as metals loading, morphological development, band engineering, and heterojunctions are systematically discussed. Finally, challenges and opportunities associated with constructing COF-based catalysts as future research prospective for chemistry and materials science are highlighted.     

Recent progress and challenges in photocatalytic water splitting using layered double hydroxides (LDH) based nanocomposites

The worldwide energy demand is steadily increasing and estimated to be doubled by the year 2050 due to a continuous hike in economies and population. A large part of the global energy requirement procures using traditional energy sources such as fossil fuels, which are non-renewable. Also, their excessive consumption imparts negative impacts on the environment by CO₂, and CO emissions, which constantly increase the average global temperature. Therefore, the need for a more reliable, sustainable, inexpensive, renewable and environmentally-friendly form of energy is imperative. From these perspectives, hydrogen energy is emerging as one of the most promising alternatives to overcome rising energy demand with a zero-carbon footprint.Herein, various layered double hydroxides (LDH) nanocomposite owing to their attractive physicochemical properties and synergistic effect with other materials in the field of hydrogen production are reviewed. Why the class of LDHs materials is critical and their ideographic properties which make them promising materials in the field of water splitting via photocatalysis and electrocatalysis are also discussed. The synthetic methods of LDHs based nanocomposites fabrication are summarized. Various challenges and strategies from the viewpoint of a different method of hydrogen production through LDHs are reported. Additionally, multiple techniques like surface plasmon resonance (SPR), heterojunction formation, and doping with co-catalyst to increase the efficiency for photocatalytic hydrogen production are also presented. Hopefully, this review will help the readers explore highly efficient, inexpensive and stable LDH catalysts toward photocatalytic water splitting.     

MoSe2 regulates Ce-doped NiFe layered double hydroxide for efficient oxygen evolution reaction: The increase of active sites

Oxygen evolution reaction (OER) is a common reaction in many sustainable energy conversion systems. However, it has become a bottleneck in the development of sustainable energy conversion systems because of its slow kinetics, especially in the common electrolytic water reaction. At present, although there are a lot of researches on OER's catalysts, it is still a great challenge. In this work, a new type of composite was prepared by simple co-precipitation method and Hydrothermal, which is composed of Ce-doped NiFe Layered Double Hydroxide (LDH) and MoSe₂. The electrochemical test results of OER show that the overpotential of 6.7%Ce–NiFe LDH@MoSe₂ is 221 mV at 10 mA/cm², which is better than that of NiFe LDH (409 mV). And it is better than most of the reported OER catalysts in literature, including precious metal catalysts. Simultaneously, 6.7%Ce–NiFe LDH@MoSe₂ also has smaller Tafel slope (35.8mV/dec), larger ESCA (6689 cm²), long-time stability and selectivity with 92.1% Faraday efficiency. The excellent OER performance of 6.7%Ce–NiFe LDH@MoSe₂ benefits from the increase of active and defective sites and the interface coordination between MoSe₂ and Ce–NiFe LDH.     

Synthesis of hollow carbon-incorporated NiCoM (M = Mn,Cu, Zn) layered double hydroxide nanocages for hybrid supercapacitors

Nanostructures and compositions are the most crucial aspects in the design of electrode materials with excellent properties for hybrid supercapacitors (HSCs). In this study, bimetallic CoM-zeolitic imidazolate framework-67 (CoM-ZIF-67, M = Mn, Cu, and Zn) derived nanosheet-constructed hollow carbon-incorporated NiCoM layered double hydroxide nanocages (NiCoM-LDH/C) are successfully synthesized via the thermal annealing and subsequent etching/ion-exchange reaction. As a consequence, the NiCoM-LDH/C materials exhibit significantly improved electrochemical performance. Specifically, the optimized NiCoMn-LDH/C electrode possesses an excellent capacity performance of 888.3 C g^?1 at 1 A g^?1. Moreover, the HSC device assembled by NiCoMn-LDH/C and active carbon delivers a remarkable energy density of 46.5 Wh kg^?1 at a power density of 792.5 W kg^?1 and possesses superior cyclic stability with about 92.05% capacity retention after 5000 cycles. This work may offer a feasible and effective approach for the synthesis of carbon-incorporated ternary layered double hydroxide nanocage materials for high-performance HSC applications.     

Boosting charge transfers in cadmium sulfide nanorods with a few layered Ni-doped MoS2 nanosheets for enhanced photocatalytic hydrogen evolution

The molybdenum sulfide (MoS₂) is a promising low-cost photocatalyst aimed at the hydrogen production reactions, however, obtaining a detailed understanding of its catalytic site has proved to be a challenging task. Several studies indicated that the active sites for catalytic reaction are mainly associated with the edge sites of 2D-layered MoS₂, and their basal plane (in-plane) displays poor activity toward catalytic reactions. Herein, we established the simple approaches to enhance the activity of MoS₂ by conversion of in-plane active sites into active surface edge sites by transition metal (Ni) doping followed by exfoliation. These activated MoS₂ was utilized for enormous upgrading of CdS photocatalytic activity for hydrogen production and is roughly 249 mmol h^?1 g^?1, which is 70 times higher than pure CdS, showed ～140 h stable H₂ production. The amended conductivity, improved surface area and huge active sites are extremely advantageous properties expanded by metal doping to MoS₂ and exfoliation. Additionally, another reason for the enhanced activity of Ni–MoS₂/CdS system was due to promotion of catalytic kinetics by Ni and Mo sits, they are admirable activity of water dissociation and higher ability of hydrogen adsorption correspondingly. These modifications made of superior photogenerated charge carriers’ separation and migration for effective utilization. As far as we know, this system demonstrates the utmost effective performance among inclusive reported MoS₂ based CdS composites. Remarkably, these outcomes will have abundant potential for the progress of immensely actual photocatalytic systems.     

Electrochemical properties of nickel-aluminum layered double hydroxide/carbon composite fabricated by liquid phase deposition

Nickel-aluminum layered double hydroxide/carbon (Ni-Al LDH/C) composites have been fabricated using a mixed solution of {Al(NO₃)₃·9H₂O and H₃BO₃} as fluoride scavengers in the liquid phase deposition (LPD) process. The amount of divalent Ni²⁺ substituted by trivalent Al³⁺ within the lattice of α-Ni(OH)₂ was controlled by the concentration of Al(NO₃)₃·9H₂O solution. X-ray diffraction studies reveal pure phase Ni-Al LDH, isostructural and isomorphic to α-Ni(OH)₂ with higher interlayer distance. The electrochemical properties of the cathode materials containing 0, 8.6, 13.8, 17.8, 21.3 and 23.4 Al% were evaluated by the means of charge-discharge and cyclic voltammetry measurements. The overall comparison indicates that Ni-Al LDH/C composites have higher electrochemical performance than pure α-Ni(OH)₂/C composite. The cathode with 17.8 Al% exhibits the best performance at 1 C compared to other Al³⁺ contents; a much lower voltage plateau, well separated from the oxygen evolution at the end of the charging as well as a single flat and high discharge plateau with a discharge capacity of 376.9 mAh g_comp⁻¹. Short term durability test for 80 cycles showed that the electrode containing 13.8 Al% has the highest discharge rate at 2 C. The range of Al substitution 13.8-17.8 Al% provides a good electrochemical response.     

CuAl layered double hydroxide as a highly efficient electrocatalyst for the electrolysis of water into hydrogen and oxygen fuels

The production of green H₂ through water electrolysis processes has become a prominent technology to deal with energy and environmental crisis worldwide. The total energy consumption of electrolysis processes can be reduced by the development of low-cost electrocatalysts. In this paper, we report first time the synthesis of a highly efficient 2D CuAl LDH electrocatalyst to produce the green H₂. The electrocatalyst was characterized with the help of various analytical instruments such as FT-IR, XRD, BET, TGA, ICP-OES, and XPS. The morphological characterization was done by SEM and TEM. The electrochemical characterization such as CV, LSV, Tafel plot, and EIS was done in acidic, basic, seawater, and alkaline seawater medium. It was found that CuAl LDH electrocatalyst exhibits a good current density of 100 mA/cm² at a potential of 1.178 V in acidic medium and 10 mA/cm² at 1.114V in seawater medium. It was investigated that the CuAl LDH behaves as a bifunctional electrocatalyst and exhibits excellent HER and OER activity in an acidic medium. The effect of temperature on the efficiency of the electrocatalyst under the above electrolyte mediums was also studied. The electrochemical data suggests that the CuAl LDH electrocatalyst can be utilized in an alkaline/PEM electrolyzer to produce the green H₂ at an industrial scale with optimum cost.     

NiFe layered double hydroxide as an efficient bifunctional catalyst for electrosynthesis of hydrogen peroxide and oxygen

Two electron oxygen reduction reaction to produce hydrogen peroxide (H₂O₂) is a promising alternative technique to the multistep and high energy consumption anthraquinone process. Herein, Ni–Fe layered double hydroxide (NiFe-LDH) has been firstly demonstrated as an efficient bifunctional catalyst to prepare H₂O₂ by electrochemical oxygen reduction (2e^? ORR) and oxygen evolution reaction (OER). Significantly, the NiFe-LDH catalyst possesses a high faraday efficiency of 88.75% for H₂O₂ preparation in alkaline media. Moreover, the NiFe-LDH catalyst exhibits excellent OER electrocatalytic property with small overpotential of 210 mV at 10 mA cm^?2 and high stability in 1 M KOH solution. On this basis, a new reactor has been designed to electrolyze oxygen and generate hydrogen peroxide. Under the ultra-low cell voltage of 1 V, the H₂O₂ yield reaches to 47.62 mmol g_cat^?1 h^?1. In order to evaluate the application potential of the bifunctional NiFe-LDH catalyst for H₂O₂ preparation, a 1.5 V dry battery has been used as the power supply, and the output of H₂O₂ reaches to 83.90 mmol g_cat^?1 h^?1. The excellent electrocatalytic properties of 2e^? ORR and OER make NiFe-LDH a promising bifunctional electrocatalyst for future commercialization. Moreover, the well-designed 2e^? ORR-OER reactor provides a new strategy for portable production of H₂O₂.     

The coralline cobalt oxides compound of multiple valence states deriving from flower-like layered double hydroxide for efficient hydrogen generation from hydrolysis of NaBH4

Efficient hydrogen storage, transportation and generation are key-technology for future hydrogen economy. Sodium borohydride (NaBH₄) stands out as promising hydrogen energy carrier with merits of high volumetric density and environmentally benign hydrolysis products. Flower-like layered double hydroxide α-Co(OH)₂ with intercalation of B species was synthesized via hydrothermal crystallization method using sodium tetraphenylboron as source of B and alkaline, which makes it different from the previous supporting materials. Pure or mixed cobalt oxides with different valence states containing B (CoO/B, Co₃O₄/B, Co+CoO/B, CoO+Co₃O₄/B) were subtly prepared via controlling calcination temperature, time and atmosphere for sodium borohydride hydrolysis. Coral-like CoO+Co₃O₄/B displayed superior hydrogen generation rate (6478 ml_H2·min^?1·g^?1_metal) with arrhenius activation energies of 41.14 kJ/mol for NaBH₄ hydrolysis in alkaline solutions compared to those reported pure precious metals. The out-standing catalytic performance of CoO+Co₃O₄/B may be attributed to electron transfer among cobalt oxide. DFT calculation indicates NaBH₄ hydrolysis undergoes a reaction path on CoO+Co₃O₄ surface with lower relative energies.     

Effect of in situ growth of NiSe2 on NiAl layered double hydroxide on its electrocatalytic properties for methanol and urea

With high energy density and low theoretical potential, the methanol oxidation (MOR) and urea oxidation (UOR) are often used as substitute reactions to the oxygen evolution reaction (OER). As one of the popular non-precious metal catalysts for the MOR/UOR research in recent years, nickel-based layered double hydroxides (LDHs) have abundant active sites and low cost, but suffer from poor catalytic activity and poor stability. In the present study, we prepared NiAl LDH and then grew NiSe₂ in situ on its surface at different temperatures, and the catalyst obtained at 450 °C (4NiAlSe-450) exhibited excellent MOR/UOR electrocatalytic performance with potentials of 1.37 V vs. RHE and 1.36 V vs. RHE at a current density of 10 mA cm⁻², respectively, which were much higher than those of NiAl LDH (1.42 V vs. RHE and 1.39 vs. RHE). Chronoamperometry curves of 4NiAlSe-450 at 1.5 V potential showed that the methanol/urea oxidation was stable for more than 3 h. The physicochemical properties of 4NiAlSe-450 were analyzed by using X-ray diffraction, X-ray photoelectron spectroscopy and other techniques, and the results showed that the NiSe₂ nanoparticles were successfully grown in situ on the calcined layered structure, and therefore the excellent MOR/UOR electrocatalytic performance of 4NiAlSe-450 may be due to the synergistic effect between the NiAl composite oxides and NiSe₂.     

Electrochemical hydrogen evolution reaction over Co/P doped carbon derived from triethyl phosphite-deposited 2D nanosheets of Co/Al layered double hydroxides

Hydrogen is widely considered an emissions-free alternative energy carrier for sustainable energy devices, such as fuel cells and nickel-metal hydride batteries. Recently, electrochemical hydrogen evolution reaction (HER) from water splitting has been attracted as an eco-friendly process for producing hydrogen. Herein, we report a Co/P-doped carbon material (Co/P/C) derived from cobalt-aluminum layered double hydroxide nanosheets (LDHs) for HER. The Co/P/C was synthesized using triethyl phosphite as phosphate and carbon sources by a one-step chemical vapor deposition (CVD) process. The regular arrangement of Co and Al atoms in the precursor LDHs allowed Co/P species to be highly dispersed under optimized CVD conditions. The carbon nanotube formed by the CVD process improved the catalytic activity of Co/P/C. The optimized Co/P/C exhibits a low overpotential of 240 mV at ?10 mA cm^?2 for HER, comparable to the commercial Pt/C catalyst. This work provides a new direction for developing transition-metal and hetero-atom co-doped carbon materials with high catalytic activity for HER.     

Interfacial engineering to construct 2D-2D NiCo-LDH/g-C3N4 heterojunctions for enhanced photocatalytic hydrogen production performance

Photocatalytic water splitting provides a green method to solve the energy shortage issue. Combine two-dimensional carbon nitride nano sheets with other two-dimensional semiconductors can effectively increase the construct area and improve the utilization of photogenerated charges. Herein, 2D-2D NiCo-LDH/g-C₃N₄ composites were successfully prepared by a simple hydrothermal method. The lamellar NiCo-LDH was grown in situ on g-C₃N₄, in which way the hydrogen production rate was enhanced by about 21 times, reaching 755 μmol·g⁻¹·h⁻¹. According to the results of density functional theory （DFT） calculations, an S-type heterojunction is successfully constructed, which achieves the spatial separation of semiconductor photogenerated electron-hole with guaranteed strong redox capability. This work emphasizes that effective transport channels for transfer and separation of photogenerated charges can be created through efficient interfacial regulation strategy.     

In situ preparation of N doped orthorhombic Nb2O5 nanoplates /rGO composites for photocatalytic hydrogen generation under sunlight

The synthesis of nitrogen doped orthorhombic niobium oxide nanoplates/reduced graphene oxide composites (NNb₂O₅/rGO) and their photocatalytic activity towards hydrogen generation from water and H₂S under natural sunlight has been demonstrated, uniquely. Nanostructured NNb₂O₅/rGO is synthesized by in situ wet chemical method using urea as a source of nitrogen and optimized by varying percentage of graphene oxide (GO). X?ray diffraction (XRD) study reveals that NNb₂O₅ have orthorhombic crystal structure with crystalline size, 35 nm. Further, X?ray photoelectron spectroscopy (XPS) confirm the presence of nitrogen and rGO in NNb₂O₅/rGO nanocomposite. Morphological features of (NNb₂O₅/rGO) were examined by FE?SEM and FE?TEM showed Nb₂O₅ nanoplates of diameter 25–40 nm anchored on 2D rGO. Diffuse reflectance spectra depicts the extended absorbance in the visible region with band gap of 2.2 eV. Considering the band gap in the visible region, the photocatalytic hydrogen generation from water and H₂S has been performed. The 1 wt % rGO hybridized NNb₂O₅ (S2) exhibited superior photocatalytic hydrogen generation (537 μmol/h) from water and (1385 μmol/h) from H₂S under sunlight. The improved photocatalytic activity is attributed due to an extended absorbance in the visible region, modified electronic structure upon doping and formation of well defined NNb₂O₅/rGO interface, provides large surface area, accelerates the supression of electron and hole pairs recombination rate. In our opinion, this works may provides facile route for energy efficient and economic approach for fabrication of NNb₂O₅/rGO nanocomposites as a visible light active photocatalyst.     

A promising synergistic effect of nickel ferrite loaded on the layered double hydroxide-derived carrier for enhanced photocatalytic hydrogen evolution

In this study, an attempt was made to modify the photocatalytic properties of an ion-exchangeable semiconductor material to enhance the efficiency of hydrogen production. Visible-light active NiFe₂O₄ was loaded onto NiZn/Cr layered double hydroxide (LDH) (Ni/Zn molar ratio = 75/25) with the Fe/Cr molar ratio of 0.005, 0.010, and 0.015 as cocatalyst through a simple solvothermal process and subsequently subjected to calcination at temperature of 500 °C. The results revealed that the presence of the loaded cocatalyst significantly facilitated the photocatalytic activity and the mixed oxide with Fe/Cr = 0.010 displayed the highest photocatalytic activity for visible light-induced H₂ generation. The optimal amount of hydrogen evolution reached to 269.44 μmolh^?1 under visible light (λ > 420 nm), which is far superior to that of the pristine NiZn/Cr LDH-derived oxides material (130.85 μmolh^?1), indicating the important catalytic role of NiFe₂O₄. The significant enhancement in photoactivity was attributed to the synergistic effect of nickel ferrite attached on the external surface of the calcined brucite-like sheets of the LDH. The cocatalyst NiFe₂O₄ nanoparticles increase the donor or acceptor levels in comparison with the pristine NiZn/Cr LDH-derived semiconductor oxide. Moreover, the existence of sheet-like LDH-derived carrier could inhibit the rapid recombination of photogenerated electrons and holes.