Photocatalyst For Hydrogen Evolution Research Articles

Dual-channels separated mechanism of photo-generated charges over semiconductor photocatalyst for hydrogen evolution: Interfacial charge transfer and transport dynamics insight

Photocatalytic water splitting to produce hydrogen is one of the most promising strategies to alleviate the energy crisis and environmental pollution. Nevertheless, the rapid recombination of photo-induced electron-hole pairs in the volume phase and surface of the semiconductor photocatalysis severely limits the activity of the photocatalysts. Herein, the hollow tubular carbon nitride (HTCN) was modified by the introduction of S element doping and anchoring carbon dots (CDs) on the surface to prepare CDs/S-HTCN composite, which exhibits boosted photocatalytic hydrogen evolution rate (∼9284 μmol h−1 g−1) compared to and S-HTCN (∼3120 μmol h−1 g−1) and HTCN (∼2086 μmol h−1 g−1). The enhancement of photocatalytic activity is mainly ascribed to the adjusted the electronic structure and optical properties of HTCN by S atoms doping for promoting rapid volume phase charge separation efficiency and captured and stored electrons from conduction band of S-HTCN by CDs loading for accelerating the surface separation efficiency of the electron-hole pairs. This dual-channels separation mechanism of photo-generated charges can provide insights into the development of composite photocatalyst with high activity and stability.

Synthesis of Narrow-Band-Gap GaN:ZnO Solid Solution for Photocatalytic Overall Water Splitting

The solid solution of GaN and ZnO (GaN:ZnO) is a promising photocatalyst applicable to visible-light-driven overall water splitting. However, the band gap of active GaN:ZnO remains as large as ca. 2.7 eV because of the loss of ZnO during the widely applied NH3 nitridation process. Herein, particulate GaN:ZnO exhibiting a band gap of 2.3 eV was synthesized via calcination of a mixture of Ga2O3, Zn, and NH4Cl in a sealed evacuated tube. The synthesis method was also featured with a high nitrogen utilization rate of 87%. The prepared narrow-band-gap GaN:ZnO was active in the overall water-splitting reaction. In the presence of sacrificial reagents, the apparent quantum yields of GaN:ZnO at 420 nm for H2 and O2 generation were 5.1 and 14.3%, respectively. GaN:ZnO was applied as an oxygen evolution photocatalyst to construct a Z-scheme overall water-splitting system with SrTiO3:Rh as a hydrogen evolution photocatalyst, which achieved a solar-to-hydrogen energy conversion efficiency of 3.7 × 10–2% and a remarkable photochemical stability up to 100 h. This work provides an approach to the synthesis of narrow-band-gap GaN:ZnO solid solution and shows the potential of this material in H2 production from water under long-wavelength visible light.

Highly Efficient Photocatalytic Hydrogen Evolution over Mo-Doped ZnIn2S4 with Sulfur Vacancies.

The introduction of impure atoms or crystal defects is a promising strategy for enhancing the photocatalytic activity of semiconductors. However, the synergy of these two effects in 2D atomic layers remains unexplored. In this case, the preparation of molybdenum-doped thin ZnIn2S4-containing S vacancies (Mo-doped Sv-ZnIn2S4) is conducted using a one-pot solvothermal method. The coordination of Mo doping and S vacancies not only enhances visible light absorption and facilitates the separation of photogenerated carriers but also provides many active sites for photocatalytic reactions. Meanwhile, the Mo-S bonds play function as high-speed channels to rapidly transfer carriers to the active sites, which can directly promote hydrogen evolution. Consequently, Sv-ZnIn2S4 with an optimized amount of Mo doping exhibits a high hydrogen evolution rate of 5739 μmol g-1 h-1 with a corresponding apparent quantum yield (AQY) of 21.24% at 420 nm, which is approximately 5.4 times higher than the original ZnIn2S4. This work provides a new strategy for the development of highly efficient and sustainable 2D atomic photocatalysts for hydrogen evolution.

Efficient and Stable Catalytic Hydrogen Evolution of ZrO2/CdSe-DETA Nanocomposites under Visible Light

Composite photocatalysts are crucial for photocatalytic hydrogen evolution. In this work, ZrO2/CdSe-diethylenetriamine (ZrO2/CdSe-DETA) heterojunction nanocomposites are synthesized, and efficiently and stably catalyzed hydrogen evolution under visible light. X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscope (HRTEM) confirm the formation of heterojunctions between ZrO2 (ZO) and CdSe-DETA (CS). Ultraviolet–visible spectroscopy diffuse reflectance spectra (UV-vis DRS), Mott–Schottky, and theoretical calculations confirm that the mechanism at the heterojunction of the ZrO2/CdSe-DETA (ZO/CS) nanocomposites is Type-I. Among the ZO/CS nanocomposites (ZO/CS-0.4, ZO/CS-0.6, and ZO/CS-0.8; in the nanocomposites, the mass ratio of ZO to CS is 0.1:0.0765, 0.1:0.1148, and 0.1:0.1531, respectively). ZO/CS-0.6 nanocomposite has the best photocatalytic hydrogen evolution activity (4.27 mmol g−1 h−1), which is significantly higher than ZO (trace) and CS (1.75 mmol g−1 h−1). Within four cycles, the ZO/CS-0.6 nanocomposite maintains an efficient catalytic hydrogen evolution rate. Due to the existence of the heterojunction of the composites, the photogenerated electron-hole pairs can be effectively separated, which accelerates the photocatalytic hydrogen evolution reaction and reduces the progress of photocorrosion. This work reveals the feasibility of ZO/CS nanocomposite photocatalysts for hydrogen evolution.

Highly efficient visible-light-driven photocatalytic hydrogen production on Cu7S4/Zn0.2Cd0·8S p-n binary heterojunctions

In this work, a series of ZnxCd1-xS solid solutions are firstly prepared by a solvothermal process. The optimized composition of ZnxCd1-xS solid solution is determined to be Zn0·2Cd0.8S. On this basis, the Cu7S4/Zn0·2Cd0·8S composite photocatalyst with a binary p-n heterojunction has been synthesized by a co-precipitation process followed by a solvothermal method. Owning to the synergistic effect of the heterojunction structure in the interface of Cu7S4 (p-type) and Zn0·2Cd0·8S (n-type) and the built-in electric field in binary p-n heterojunction, the as-prepared Cu7S4/Zn0·2Cd0·8S composite photocatalyst exhibits a significantly improved photocatalytic activity toward hydrogen production from water with visible light response, which is approximately 5.0 times and 16.5 times higher than of pristine Zn0·2Cd0·8S and CdS, respectively. The possible photocatalytic mechanism has been proposed basing on a series of experimental results. The current work might be valuable inspirations for designing highly efficient heterojunction composite photocatalyst for solar hydrogen evolution.

Boosted solar water photoreduction by conjugated polymer-mediated tandem charge transfer

Semiconductor materials anchored with transition metal cluster are promising photocatalysts for photocatalytic hydrogen evolution. In this paper, Co, N-co-doped graphene modified thin mesoporous carbon nitride (Co-NG/TMCN) was be synthesized through electrostatic adsorption treatment. Extensive characterization was used to explore the morphology, structures and optical properties of the as-prepared photocatalysts. The 10 wt% Co-NG/TMCN exhibited the high photocatalytic hydrogen evolution rate (2949 μmol g−1) within 4 h visible light irradiation, which was about 113 times than that of the pure TMCN (26 μmol g−1). Co-NG material with excellent electrical conductivity played a major role in accelerating charge transfer from TMCN material to cobalt atomic clusters. The photocatalytic hydrogen evolution performance of Co-NG/TMCN material was effectively improved. Consequently, a feasible approach for doping transition metal clusters to enhance photocatalytic activity was provided.

The construction of 3D hierarchical CdS/NiAl-LDH photocatalyst for efficient hydrogen evolution

The development of excellent photocatalysts for hydrogen evolution is of great significance to solving the global energy crisis. In this work, a novel 3D hierarchical CdS/NiAl-LDH photocatalyst was fabricated by a facile electrostatic assembly strategy, which was composed of 1D CdS nanorods and 3D flower-like NiAl-LDH microspheres. Under the visible irradiation, the CNA-20 hierarchical photocatalyst presents the optimum hydrogen evolution rate achieved to 3.24 mmol g−1 h−1, which is improved 6.23-fold in comparison with the pure CdS. Through the analysis of energy band structures and first-principles calculation, the type-Ⅱ charge transfer mechanism was proposed. Driven by the built-in electric field, as well as the effect of intimate interface contact of CdS and NiAl-LDH, the photogenerated charge could be achieved rapidly separate and migrate, which effectively promotes the H2 evolution. This well-designed synergistic 1D/3D interface interaction and provides an economic approach to rationally developing metal-free photocatalysts for hydrogen production.

Morphology engineering ultrathin nitrogen-doped carbon Co-FeP derived from Co-Fe Prussian Blue Analogs for wide spectrum photocatalytic H2 evolution

The design and development of economical, efficient and stable photocatalyst for photocatalytic hydrogen evolution is a frontier subject of sustainable energy research. In this work, a morphology engineered ultrathin nitrogen-doped carbon Co-FeP (Co-FeP@NC) derived from Co-Fe Prussian Blue Analogs (Co-Fe PBA) for wide spectrum photocatalytic hydrogen evolution. We demonstrate the versatility of a self-templated epitaxial growth strategy for construction of single-crystalline hollow nanostructured PBA (Co-Fe PBA cages, frames and boxes) with different geometries by adjusting the growth kinetics. Co-FeP@NC photocatalysts have tunable band structures by adjusted phosphating degree and all have a narrow band gap. In addition, the catalysts with different morphologies have different electronic structures, and surface nitrogen-doped carbon layer increases electron transfer rate, which makes the photocatalytic hydrogen evolution activity increase significantly. The Co-FeP@NC-4 cages exhibit the highest photocatalytic hydrogen evolution rate of 13309.4 μmol h−1 g−1 under visible light irradiation with EY as a photosensitizer and TEOA as an electron donor. Additionally, a high apparent quantum efficiency (8.38 % at 520 nm) and an excellent cycle stability was also achieved over Co-FeP@NC-4 cages. The larger specific surface area, strong light absorption ability and fast photogenerated electron-hole pairs separation efficiency of Co-FeP@NC cages may be responsible for the significantly improved photocatalytic hydrogen evolution activity. This work has provided an effective strategy for synthesis of nanostructures with different geometric topologies derived from PBA and recognizing their morphology-dependent photocatalytic activity.

Vacancy-induced tensile strain of CdS/Bi2S3 as a highly performance and robust photocatalyst for hydrogen evolution

Lattice strain is a new strategy for promoting photocatalytic activity in order to source more sustainable energy. Vacancy-induced strain is an effective tactic for lattice deformation. Herein, a CdS/Bi2S3 heterojunction structure containing sulfur vacancies (CdS/Bi2S3-VS) is synthesized by a one-step solvothermal method. When there are sulfur vacancies in the Bi2S3 lattice (Bi2S3-VS), the surrounding atoms move toward sulfur vacancies. This phenomenon lengthens the bonds between surrounding atoms, resulting in tensile stress. Strain engineering adjusts the energy band structure to reduce the interface barrier height, thus effectively improving the interface charge transfer rate. Moreover, density functional theory (DFT) calculations explore the influence of different strain levels on the band structure and Gibbs free energy. The strain-regulated band structure provides a new approach and effectively reduce the interface barrier.

Why Do Sulfone-Containing Polymer Photocatalysts Work So Well for Sacrificial Hydrogen Evolution from Water?

Many of the highest-performing polymer photocatalysts for sacrificial hydrogen evolution from water have contained dibenzo[b,d]thiophene sulfone units in their polymer backbones. However, the reasons behind the dominance of this building block are not well understood. We study films, dispersions, and solutions of a new set of solution-processable materials, where the sulfone content is systematically controlled, to understand how the sulfone unit affects the three key processes involved in photocatalytic hydrogen generation in this system: light absorption; transfer of the photogenerated hole to the hole scavenger triethylamine (TEA); and transfer of the photogenerated electron to the palladium metal co-catalyst that remains in the polymer from synthesis. Transient absorption spectroscopy and electrochemical measurements, combined with molecular dynamics and density functional theory simulations, show that the sulfone unit has two primary effects. On the picosecond timescale, it dictates the thermodynamics of hole transfer out of the polymer. The sulfone unit attracts water molecules such that the average permittivity experienced by the solvated polymer is increased. We show that TEA oxidation is only thermodynamically favorable above a certain permittivity threshold. On the microsecond timescale, we present experimental evidence that the sulfone unit acts as the electron transfer site out of the polymer, with the kinetics of electron extraction to palladium dictated by the ratio of photogenerated electrons to the number of sulfone units. For the highest-performing, sulfone-rich material, hydrogen evolution seems to be limited by the photogeneration rate of electrons rather than their extraction from the polymer.

Anchoring highly distributed Pt species over oxidized graphitic carbon nitride for photocatalytic hydrogen evolution: The effect of reducing agents

Platinum (Pt) as a cocatalyst over graphitic carbon nitride (g-C3N4) is the main active site in the hydrogen evolution reaction (HER). Therefore, controlling the properties of Pt is significant to achieve a high H2 production yield in which the reduction step of the Pt precursor is an important factor. In this study, we prepared Pt-loaded chemically oxidized g-C3N4 photocatalysts for photocatalytic hydrogen evolution using different Pt deposition methods-chemical reduction with hydrazine, hydrogen reduction, and photoreduction. The hydrogen evolution rate of the chemically oxidized Pt/g-C3N4 photocatalysts prepared via hydrogen reduction (1152.8 µmol g-1h−1) was the highest compared to those prepared via chemical reduction (409.9 µmol g-1h−1) and photoreduction (583.7 µmol g-1h−1). The hydrogen reduction method with a fine reducing ability could achieve a uniform distribution of Pt nanoparticles anchored onto the chemically oxidized g-C3N4 nanosheets while maintaining homogeneity between the Pt precursor – reducing agent – g-C3N4. Furthermore, during hydrogen reduction, the greatest ─C═O content and lowest concentrations of ─COOH and ─COH groups on the g-C3N4 surface resulted in an extremely high Pt2+/Pt0 ratio, a strong electronic Pt–g-C3N4 interaction, and the highest charge transfer efficiency, enhancing the hydrogen evolution rate.

Double-shelled CeO2 coupled CdZnS nanoparticles as an efficient heterojunction visible light photocatalyst for hydrogen evolution

Designing of novel semiconductor photocatalysts toward high-efficient catalytic H2 generation has played a potential role in developing sustainable energy. Here, nanostructured CeO2/CdZnS/ZnO composite material has been synthesized through simple hydrothermal process. The present photocatalyst exhibits high photocatalytic activity for H2 generation under visible light irradiation (λ > 420 nm). It can be possibly explained: First, the ZnO layer formed on double-shelled CeO2 hollow spheres (D-CeO2) by the priority adsorption of Zn2+ exhibits both efficient hole consumption and photo-corrosion inhibition. Second, superior charge separation and charge transfer efficiency originates from the Z-scheme CeO2/CdZnS heterojunction.

Partial magnetic ion substitution of BiFeO3 Multiferroic photocatalyst for hydrogen evolution from water splitting

BiFeO 3 as a p-type photocatalyst in BiFeO 3 –CdWO 4 p-n heterojunction was modified by partial substitution of divalent Co 2+ and Ni 2+ at Fe-site to enhance the photocatalytic performance for H 2 evolution from pure water splitting. At high impurity concentrations, XRD and Raman spectroscopy revealed a phase transition from rhombohedral to orthorhombic/tetragonal with higher crystal symmetry due to larger ionic radii of Co 2+ and Ni 2+ relative to that of Fe 3+ . The excess amount of impurities also resulted in the formation of nickel ferrite (NiFe 2 O 4 ), cobalt ferrite (CoFe 2 O 4 ), sillenite (Bi 25 FeO 40 ) and mullite (Bi 2 Fe 4 O 9 ) as secondary phases. The high resolution XPS spectra of O 1s and Fe 2p indicted that the concentration of oxygen vacancy and Fe 2+ : Fe 3+ increased with doping BiFeO 3 , which is due to the structural distortion and defection. Moreover, magnetic property of BiFeO 3 was promoted by Co and Ni doping so that the residual magnetization increased from 0.009 emu/g up to 0.061 and 0.068 emu/g by 9 mol.% doping of Ni and Co, respectively. The enhanced magnetism can be attributed to the net magnetic moment caused by different magnetic moment of Fe 3+ , Co 2+ and Ni 2+ as well as the structural defection that may be a reason for spin spiral suppression. Doping with Co and Ni led to reducing band gap energy, suppression of charge recombination, and increment of charge density and mobility. The efficiency of photocatalytic H 2 evolution increased from 268.9 μmol/h gcat by pure BFO up to 449.6 and 494.7 μmol/h gcat by 9 mol.% Ni and Co doping, respectively. • BiFeO 3 was modified by substitution of Fe 3+ with larger divalent Co 2+ and Ni 2+ . • Crystal distortion and phase transition were revealed by XRD and Raman analyses. • Magnetic property was modified as a result of crystal distortion. • Charge recombination was efficiently suppressed by Co and Ni doping. • Photocatalytic H 2 evolution was boosted by 9 mol.% Co and Ni doping.

In-situ exsolved NiS nanoparticle-socketed CdS with strongly coupled interfaces as a superior visible-light-driven photocatalyst for hydrogen evolution

Herein, a NiS nanoparticle-socketed CdS photocatalyst (NiS/CdS-e) is developed by hydrothermal sulfurization of Ni-doped Cd(OH)2 precursor, where the Cd(OH)2 particles are converted into CdS while the doped Ni species are exsolved and socketed on the surfaces of CdS. 2% NiS/CdS-e presents a high H2 evolution rate of 18.9 mmol g−1 h−1 with an apparent quantum efficiency (AQE) of 13.9% at 420 nm, much superior to those of pristine CdS (0.5 mmol g−1 h−1) and 2% NiS/CdS-h (9.9 mmol g−1 h−1) prepared by impregnation-hydrothermal sulfurization. The enhanced activity originates from the strongly coupled interface between exsolved NiS and CdS that efficiently promote the charge separation, while the exsolved NiS nanoparticles serve as highly active H2 evolution sites. Moreover, the strongly coupled interfaces enable improved H2 evolution stability for 2% NiS/CdS-e over a 30-h cycling reaction. This work provides an effective strategy toward strongly coupled cocatalyst/semiconductor photocatalysts for efficient solar energy conversion.

Integrating electronic structure regulation and dynamic active sites construction on NixCd1-xS-Ni0 photocatalyst for efficient hydrogen evolution

Regulating electronic structure and enriching active sites of photocatalysts are effective strategies to promote hydrogen evolution. Herein, a unique NixCd1-xS-Ni0 photocatalyst, including the surface nickel (Ni) doping and atomic Ni0 anchoring sites, is successfully prepared by Ni2+ ions exchange reaction (Ni2++ CdS → NixCd1-xS) and in-situ photo-induction of Ni0(Ni2++NixCd1-xS→hνNixCd1-xS-Ni0), respectively. As to Ni doping, the Ni replaced cadmium (Cd) atoms introduce hybridized states around the Fermi level, modulating the electronic structure of adjacent S atoms and optimizing the photocatalytic activity of sulfur (S) atoms. Besides, photogenerated Ni0 atoms, anchored on unsaturated S atoms, act as charge transfer bridges to reduce Ni2+ ions in the solution to Ni clusters (NixCd1-xS-Ni0→ne-NixCd1-xS-Ni). Subsequently, the displacement reaction of Ni clusters with protons (H+) spontaneously proceeds to produce hydrogen (H2) in an acidic solution (NixCd1-xS-Ni→2H+H2↑+Ni2++NixCd1-xS-Ni0). The equilibrium of photo-deposition/dissolution of Ni clusters realizes the construction of dynamic active sites, providing sustainable reaction centers and enhancing surface redox kinetics. The NixCd1-xS-Ni0 exhibits a high hydrogen evolution rate of 428 mmol·h−1·g−1 with a quantum efficiency of 75.6 % at 420 nm. This work provides the optimal S electronic structure for photocatalytic H2 evolution and constructs dynamic Ni clusters for chemical replacement reaction. This work provides the optimal S electronic structure for photocatalytic H2 evolution and constructs dynamic Ni clusters for displacement reaction, opening a dual pathway for efficient water reduction.

Fabrication of noble-metal-free copper-doped TiO2 nanofibers synergized with acetic acid-treated g-C3N4 nanosheets for enhanced photocatalytic hydrogen evolution

The combination of copper-doped TiO2 nanofibers (Cu-TiO2 NFs) with acetic acid-treated graphitic carbon nitride (g-C3N4) provided an efficient photocatalyst for hydrogen (H2) evolution. Nanosheets of g-C3N4 (0.2, 0.3, and 0.4 wt%) integrated with Cu-doped TiO2 NFs displayed improved photocatalytic H2 evolution efficiency. The highest H2 evolution of 1.30 mmol/g was recorded for 0.3 wt% g-C3N4 coated on Cu-TiO2 NFs, which was 18.64-fold higher than the H2 evolution of g-C3N4 alone and 8.15-fold higher than the H2 evolution of pure TiO2 NFs. As indicated by different experimental characterizations, the incorporation of photosensitizers, including copper and g-C3N4 nanosheets, enabled enhanced photoresponse and successful separation of charge carriers. Furthermore, the synergistic effect between 1D and 2D structures resulted in heterojunction formation which helped in superior charge separation consequently enhancing photocatalytic H2 evolution. Thus, this work can provide new ideas and insights for the synthesis of non-precious metal-based photocatalysts.

Direct Z-scheme ZnIn2S4 spheres and CeO2 nanorods decorated on reduced-graphene-oxide heterojunction photocatalysts for hydrogen evolution and photocatalytic degradation

Nanocomposite photocatalysts can potentially produce clean hydrogen (H2) and degrade organic pollutants such as tetracycline (TC). We present hydrothermally synthesized ternary composites of ZnIn2S4–CeO2 implanted into reduced graphene oxide (rGO) layers that outperform typical, expensive catalysts used in the hydrogen evolution reaction (HER). The structural morphology of the composite along with its H2 photocatalytic production and TC degradation ability are evaluated. The results reveal that the ZnIn2S4/rGO/CeO2 heterojunctions demonstrate higher photocatalytic activity for H2 generation and TC degradation than their bare and binary counterparts. The higher efficiency of the ZnIn2S4–rGO–CeO2 composite is attributable to the synergetic effect of rGO as an electron (e–)-transfer bridge, as evidenced by the photocurrent density and photoluminescence results. The ZnIn2S4/rGO/CeO2 ternary catalyst absorbs a wide range of wavelengths, diffuses and separates the photoinduced charge carriers quickly and efficiently, and slowly recombines e– and h+. The generated ternary composite material is then used to demonstrate plausible photocatalytic HER and degradation processes.

Solar Hydrogen Generation over Carbon Nitride Photocatalyst Promoted by Water‐Soluble Carbon Dots

AbstractSolar hydrogen generation from water is one of the promising routes to alleviate the current environmental and energy issues. Graphitic carbon nitride (g‐C3N4) has emerged as a promising photocatalyst for hydrogen evolution using visible light while withstanding harsh chemical environments. However, the high occurrence of trapped unreactive charges seriously affects the catalytic performance of g‐C3N4 in photocatalysis applications. Herein, we show that the addition of water‐soluble carbon dots (CDs) to the reaction solution will promote the relaxation of photogenerated electrons in g‐C3N4, thus effectively improving the photocatalytic performance for hydrogen evolution by two times (983.7 vs. 490.7 μmol ⋅ h−1 ⋅ g−1 for with and without CDs, respectively). The steady state properties of the reaction system are studied by ultraviolet‐visible (UV‐vis) and photoluminescence (PL) excitation/emission spectroscopy, which show that the introduction of CDs enhances the visible light absorption of the reaction system. Furthermore, the charge trapping and detrapping processes in g‐C3N4 are further revealed by using time‐resolved photoluminescence (tr‐PL) spectroscopy. The correlation between charge transfer and photocatalytic activity provides new insights into the charge separation dynamics and activity of carbon‐based photocatalysts.

Evolutionary mechanism of Ni-ZIF/CdS calcination for efficient photocatalytic hydrogen evolution

In this work, we develop Ni/Ni3S2/CdS composite photocatalytic system from annealing of CdS nanosphere coated Ni-ZIF by simple solvothermal method. The Ni/Ni3S2/CdS synthesized after calcination at 700 °C exhibits the best hydrogen evolution performance with an average hydrogen evolution rate of 2104.02 μmol/g/h, which is 152 times higher than that of pure CdS, and external quantum efficiency is 41.9% (λ = 420 nm). Using a series of characterization methods, we revealed that CdS is the photosensitizer, Ni is the catalytic active species, and Ni3S2 formed between Ni and CdS formation plays an important role in charge separation as confirmed by time resolved emission spectroscopy. In addition, the regulation of Ni loading is achieved by changing the annealing time and the molar ratio of Ni salt to CdS. These results demonstrate that Ni/Ni3S2/CdS is a favorable photocatalyst for efficient photocatalytic hydrogen evolution.

Synchronous synthesis of S-doped carbon nitride/nickel sulfide photocatalysts for efficient dye degradation and hydrogen evolution

Rational design of photocatalysts with low-cost and high-efficiency is of great significance for environmental remediation and energy utilization. Herein, the NiS-loaded on S-doped carbon nitride photocatalysts were synchronous synthesized via one-pot hydrothermal method. The activities of the photocatalysts were evaluated by photodegradation of RhB and photocatalytic hydrogen production under visible-light irradiation. It has been found that the optimal photocatalyst (SCN/NiS-1) showed outstanding photocatalytic activity of removing 98.5% RhB within 15 min and 700.9 μmol‧g−1‧h−1 H2-evolving rate with 0.89 wt% sulfur doping and 1 wt% NiS loading, respectively, which were significantly higher than pristine g-C3N4. The enhanced photocatalytic activity of SCN/NiS-1 was due to its expanded light absorption and facilitated separation or transportation of photoinduced charge carriers under the synergistic function of S doping and NiS loading. A possible mechanism of SCN/NiS-x on the improvement of the photocatalytic performance of carbon nitride was proposed based on a series of characterization analyses. This work strengthens the idea that bulk and surface engineering simultaneously affect photocatalytic activity.