Synthesis and photocatalytic H2-production activity of plasma-treated Ti3C2Tx MXene modified graphitic carbon nitride

Plasma processing technology, as a promising method to enhance photocatalytic activity of catalyst, is gradually attracting extensive interest from researchers. However, the main mechanism of plasma-treated photocatalyst on hydrogen production is not clear. In this work, 2D Ti₃C₂T_x MXene is selected as a co-catalyst of graphitic carbon nitride (g-C₃N₄), which carries out a plasma treatment (500°C) under N₂/H₂ atmosphere. Due to plasma treatment, there is a higher proportion Ti–O functional groups on surface of layered Ti₃C₂T_x MXene, especially for Ti⁴⁺. The obtained g-C₃N₄/p-Ti₃C₂T_x photocatalyst with sandwich-like structure shows an enhanced photocatalytic activity. The rate of hydrogen generation of CN/pTC3.0 sample without Pt co-catalyst is 25.4 and 2.4 times that of pure g-C₃N₄ and CN/TC3.0 samples, respectively. The improved photocatalytic activity is attributed to presence of Ti⁴⁺ due to plasma treatment, which can capture photo-induced electron from g-C₃N₄ and improve the separation of electrons and holes after visible light irradiation. The cyclic hydrogen production of the photocatalyst demonstrates good photocatalytic stability. In addition, this method of plasma treatment under N₂/H₂ atmosphere is feasible to develop a high-performance co-catalyst, which can be extended to other photocatalysts with two-dimensional structure for photocatalytic water-splitting applications.     

Preparation and photocatalytic activity of g-C3N4/TiO2 heterojunctions under solar light illumination

The solar light sensitive g-C₃N₄/TiO₂ heterojunction photocatalysts containing 20, 50, 80, and 90 wt% graphitic carbon nitride (g-C₃N₄) were prepared by growing Titania (TiO₂) nanoparticles on the surfaces of g-C₃N₄ particles via one step hydrothermal process. The hydrothermal reactions were allowed to take place at 110 °C at autogenous pressure for 1 h. Raman spectroscopy analyses confirmed that an interface developed between the surfaces of TiO₂ and g-C₃N₄ nanoparticles. The photocatalyst containing 80 wt% g-C₃N₄ was subsequently heat treated 1 h at temperatures between 350 and 500 °C to improve the photocatalytic efficiency. Structural and optical properties of the prepared g-C₃N₄/TiO₂ heterojunction nanocomposites were compared with those of the pristine TiO₂ and pristine g-C₃N₄ powders. Photocatalytic activity of all the nanocomposites and the pristine TiO₂ and g-C₃N₄ powders were assessed by the Methylene Blue (MB) degradation test under solar light illumination. g-C₃N₄/TiO₂ heterojunction photocatalysts exhibited better photocatalytic activity for the degradation of MB than both pristine TiO₂ and g-C₃N₄. The photocatalytic efficiency of the g-C₃N₄/TiO₂ heterojunction photocatalyst heat treated at 400 °C for 1 h is 1.45 times better than that of the pristine TiO₂ powder, 2.20 times better than that of the pristine g-C₃N₄ powder, and 1.24 times better than that of the commercially available TiO₂ powder (Degussa P25). The improvement in photocatalytic efficiency was related to i) the generation of reactive oxidation species induced by photogenerated electrons, ii) the reduced recombination rate for electron-hole pairs, and iii) large specific surface area.     

Enhanced photocatalytic hydrogen evolution over TiO2/g-C3N4 2D heterojunction coupled with plasmon Ag nanoparticles

2D heterojunction based on g-C₃N₄ nanosheets with other semiconductor nanosheets is a promising way to improve photocatalytic hydrogen evolution (PHE) activity over g-C₃N₄. However, current 2D heterojunction based on g-C₃N₄ are unsatisfactory due to their insufficient absorption of visible light and inefficient charge separation. In this work, Ag/TiO₂/g-C₃N₄ nanocomposites based on 2D heterojunction coupling with Ag surface plasmon resonance (SPR) were synthesized by a method combining facile wetness impregnation calcination. The PHE activity of Ag/TiO₂/g-C₃N₄ nanocomposites is attributed to the TiO₂/g-C₃N₄ 2D heterojunction and bare g-C₃N₄ nanosheet under visible light irradiation, indicating a cooperative effect between Ag and TiO₂/g-C₃N₄ 2D heterojunction. As a result of SPR effect, the composites strongly absorb visible light. In addition, the oscillating hot electrons from Ag can easily transfer to 2D heterojunction. This synergistic effect lead to sufficient visible light absorption and efficient charge separation of 2D heterojunction, which improved the PHE activity of g-C₃N₄. This work indicates that loading metal nanoparticles on 2D heterojunction as metal SPR-2D heterojunction nanocomposites may be a potential method for harvesting visible light for PHE.     

Visible light-activated degradation of microcystin-LR by ultrathin g-C3N4 nanosheets-based heterojunction photocatalyst

Microcystins (MCs) is a harmful toxin generated by blue-green algae in water, which has seriously threatened the ecological safety of water and human body. It is urgent to develop new catalysts and techniques for the degradation of MCs. A feasible electrostatic self-assembly method was carried out to synthesize BiVO₄/g-C₃N₄ heterojunction photocatalyst with highly efficient photocatalytic ability, where BiVO₄ nanoplates with exposed {010} facets anchored to the g-C₃N₄ ultrathin nanosheets. The morphology and microstructure of the heterojunction photocatalysts were identified by XRD, SEM, TEM, XPS, and BET. The g-C₃N₄ nanosheets have huge surface area over 200 m²/g and abundant mesoporous ranging from 2-20 nm, which provides tremendous contact area for BiVO₄ nanoplates. Meanwhile, the introduction of BiVO₄ led to red-shift of the absorption spectrum of photocatalyst, which was characterized by UV-vis diffuse reflection spectroscopy (DRS). Compared with pure BiVO₄ and g-C₃N₄, the BiVO₄/g-C₃N₄ heterojunction shows a drastically enhanced photocatalytic activity in degradation of microcystin-LR (MC-LR) in water. The MC-LR could be removed within 15 minutes under the optimal ratio of BiVO₄/g-C₃N₄. The outstanding performance of the photocatalyst is attributed to synergetic effect of interface Z-scheme heterojunction and high active facets {010} of BiVO₄ nanoplates, which provides an efficient transfer pathway to separate photoinduced carriers meanwhile endows the photocatalysts with strong redox ability.     

0D CoP cocatalyst/ 2D g-C3N4 nanosheets: An efficient photocatalyst for promoting photocatalytic hydrogen evolution

In this work, cobalt phosphide (CoP) nanoparticles were successfully decorated on an ultrathin g-C₃N₄ nanosheet photocatalysts by in situ chemical deposition. The built-in electric field formed by heterojunction interface of the CoP/g-C₃N₄ composite semiconductor can accelerate the transmission and separation of photogenerated charge-hole pairs and effectively improve the photocatalytic performance. TEM, HRTEM, XPS, and SPV analysis showed that CoP/g-C₃N₄ formed a stable heterogeneous interface and effectively enhanced photogenerated electron-hole separation. UV-vis DRS analysis showed that the composite had enhanced visible light absorption than pure g-C₃N₄ and was a visible light driven photocatalyst. In this process, NaH₂PO₂ and CoCl₂ are used as the source of P and Co, and typical preparation of CoP can be completed within 3 hours. Under visible light irradiation, the optimal H₂ evolution rate of 3.0 mol% CoP/g-C₃N₄ is about 15.1 μmol h⁻¹. The photocatalytic activity and stability of the CoP/g-C₃N₄ materials were evaluated by photocatalytic decomposition of water. The intrinsic relationship between the microstructure of the composite catalyst and the photocatalytic performance was analyzed to reveal the photocatalytic reaction mechanism.     

Constructing 0D/2D Z-Scheme Heterojunction of CdS/g-C3N4 with Enhanced Photocatalytic Activity for H2 Evolution

0D/2D Pt-C₃N₄/CdS heterojunction photocatalyst were fabricated with CdS quantum dots interspersed on g-C₃N₄ nanosheets via successive ionic layer absorption process. The obtained Pt-C₃N₄/CdS Z-scheme heterojunction with Pt cocatalyst deposited on g-C₃N₄ nanosheets exhibited H₂ production rate of 35.3 mmol g^?1 h^?1, which is 3.1 times higher than that of Pt-CdS/C₃N₄. The enhanced photocatalytic activity are attributed to the Z-scheme charge carrier transfer mechanism with stronger redox ability. The photocatalytic mechanism of the CdS/g-C₃N₄ composite is investigated and demonstrated in this work. It may provide unique insights to design 0D/2D Z-scheme heterojunction photocatalyst systems using a facile method for highly efficient H₂ production.

Graphic Abstract

Schematic illustration of charge transfer modulated by the metal cocatalyst selective deposition on heterojunction-type II (a) and direct Z-Scheme mechanisms (b) over the C₃N₄/CdS heterostructure composites under visible light irradiation.

     

Fabrication of g-C3N4/TiO2 heterojunction composite for enhanced photocatalytic hydrogen production

In this study, graphitic carbon nitride (g-C₃N₄) was successfully coupled with TiO₂ using hydrothermal method, to develop an advanced heterojunction photocatalyst. The interaction between g-C₃N₄ and TiO₂ was confirmed through analysis of X-Ray spectroscopy (XPS) C 1s, N 1s, O 1s high resolution core level spectra of g-C₃N₄, TiO₂ and g–C₃N₄–TiO₂ heterojucntion. Further, through valence band spectra analysis, conduction band offset (0.12 eV) and valence band offset (0.28 eV) of g–C₃N₄–TiO₂ heterojunction were estimated. Also, composite material was identified as type II heterojunction between g-C₃N₄ and TiO₂. XRD, UV–vis, BET and HRTEM were employed to understand the changes in physicochemical properties. Photocatalytic hydrogen production rates were evaluated through water splitting experiments. Under visible light irradiation highest hydrogen production rate was achieved for g–C₃N₄–TiO₂ heterojunction sample with high content of TiO₂, and was about 1041 μmol/g.h. The improved photocatalytic activity of the heterojunction material was explained in detail.     

Fabrication of magnetically recoverable Fe3O4/CdS/g-C3N4 photocatalysts for effective degradation of ciprofloxacin under visible light

Photocatalytic technology is an environmentally safe method of eliminating organic pollutants and antibiotics in wastewater. In this research, the performance of Fe₃O₄/CdS/g-C₃N₄ (FCN) photocatalyst for degradation of antibiotics was studied. The composite photocatalysts with different concentrations of g-C₃N₄ were prepared. FCN has better photocatalytic activity than degradation dyes in removal of antibiotics under visible light. This indicates that FCN could effectively hinder the recombination of carriers, and the addition of g-C₃N₄ increases the optical response range of CdS. At the same time, the introduction of Fe₃O₄ magnetic nanoparticles overcomes the problem of difficulty in recovery of the powder photocatalyst. The photocatalytic activity is not reduced to any significant after three cycles of use.     

Dual Z-scheme heterojunction g-C3N4/Ag3PO4/AgBr photocatalyst with enhanced visible-light photocatalytic activity

Recently, there has been a significant interest in developing high-performance photocatalysts for removing organic pollutants from water environment. Herein, a ternary graphitic C₃N₄ (g-C₃N₄)/Ag₃PO₄/AgBr composite photocatalyst is synthesized using an in-situ precipitation-anion-exchange process and characterized by several spectroscopic and microscopic techniques. During the photocatalytic reaction, X-ray photoelectron spectroscopy clearly illustrated the formation of metallic Ag on the g-C₃N₄/Ag₃PO₄/AgBr composite surface. The ternary composite photocatalyst demonstrated an increased photoactivity under visible light (>420 nm), achieving a complete decolorization of methyl orange (MO) in 5 min. The ternary g-C₃N₄/Ag₃PO₄/AgBr hybrid was also applied to the 2-chlorophenol degradation under visible light, further confirming its excellent photocatalytic activity. In addition, quenching experiments revealed that holes (h⁺) and O₂^?– were the major attack species in the decolorization of MO. The enhanced photoactivity of g-C₃N₄/Ag₃PO₄/AgBr results from the efficient transfer/separation of photoinduced charges with the dual Z-scheme pathway and the charge recombination sites on the formed Ag particles.     

Synthesis of MoS2/g-C3N4 as a solar light-responsive photocatalyst for organic degradation

A novel molybdenum disulfide (MoS₂) and graphitic carbon nitride (g-C₃N₄) composite photocatalyst was synthesized using a low temperature hydrothermal method. MoS₂ nanoparticles formed on g-C₃N₄ nanosheets greatly enhanced the photocatalytic activity of g-C₃N₄. The photocatalyst was tested for the degradation of methyl orange (MO) under simulated solar light. Composite 3.0 wt.% MoS₂/g-C₃N₄ showed the highest photocatalytic activity for MO decomposition. MoS₂ nanoparticles can increase the interfacial charge transfer and thus prevent the recombination of photo-generated electron–hole pairs. The novel MoS₂/g-C₃N₄ composite is therefore shown as a promising catalyst for photocatalytic degradation of organic pollutants using solar energy.     

Soft Template-Assisted Controllable Synthesis of Nanocrystalline Orthorhombic YFeO3 Decorated Porous g-C3N4 with Enhanced Hg(II) reduction

Mesoporous single-crystalline perovskite YFeO₃ nanoparticles was synthesized through a soft template-assisted approach. Mesoporous YFeO₃ NPs were decorated porous g-C₃N₄ nanosheets with variation YFeO₃ NPs percentages, and the newly synthesized photocatalysts were assessed towards Hg(II) reduction and HCOOH oxidation in aqueous solution upon visible light exposure. XRD and HR-TEM revealed the formation of single-crystalline orthorhombic YFeO₃ with uniformly dispersed and the average particle size of 10?±?5 nm_, thereby constructing a mesoporous YFeO₃/g-C₃N₄ heterojunctions for the promotion of the photocatalytic performances compared to bare YFeO₃ NPs and g-C₃N₄. 3% YFeO₃/g-C₃N₄ heterostructure revealed the highest and optimum Hg(II) reduction (100%) within 60 min, which determined 3.7 and 5 times larger than of bare YFeO₃ NPs and g-C₃N₄ obeyed by pseudo-first-order kinetics. The YFeO₃/g-C₃N₄ photocatalyst could be recycled five continuous cycles and kept remarkable photostability for long time illumination. The superior Hg(II) reduction over mesoporous YFeO₃/g-C₃N₄ heterojunction is referred to as lower recombination of carriers, the unique electronic structure, higher visible light utilization and high surface area. This work focused on constructing the YFeO₃/g-C₃N₄ heterojunction, indicating outstanding photocatalytic performances in a facile route.

     

Enhanced visible-light photocatalytic properties of g-C3N4 by coupling with ZnAl2O4

A series of g-C₃N₄/ZnAl₂O₄ composites were prepared using a conventional calcination method and the heterostructures were systematically characterized. It was found that the combination of g-C₃N₄ with ZnAl₂O₄ significantly improve their photocatalytic activities. The optimum photocatalyst of composite is at 5% (wt%) of ZnAl₂O₄, whose degradation efficiency for methyl orange (MO) was 96% within 120 min under visible-light irradiation. The formation of heterojunction between g-C₃N₄ and ZnAl₂O₄ can facilitate efficient charge separation of photogenerated electron-hole pairs, which were confirmed by electrochemical impedance spectroscopy (EIS). As a result, the photocatalytic properties of composites were enhanced.     

Insight into the adsorption and photocatalytic properties of in-situ synthesized g-C3N4/SnS2 nanocomposite

In this paper, a novel g-C₃N₄/2 wt% SnS₂ nanocomposite was successfully synthesized using an in-situ growth of SnS₂ on g-C₃N₄. X-ray diffraction (XRD), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) method, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectrometer were used to characterize the photocatalysts. Exploring adsorption behavior, as an importatnt stage during photocatalytic reactions, is of great importance. Hence, both adsorption and photocatalytic performance of the synthesized photocatalysts have been investigated in detail. The adsorption isotherm fittings exhibited that Freundlich and Langmuir-Freundlich models can be applied to the methylene blue (MB) adsorption on the photocatalysts, indicating surface heterogeneity should be considered. A pseudo-second-order model was fitted to explore the adsorption kinetics. According to the observed redshift in the Fourier transform infrared spectroscopy (FTIR) result of g-C₃N₄/SnS₂ nanocomposite, π-π interaction was dominant during MB adsorption. Also, a slight redshift and significant PL intensity reduction in g-C₃N₄/SnS₂ nanocomposite led to 96% photocatalytic efficiency after 180 min under visible light radiation. The kinetics of photodegradation over g-C₃N₄/SnS₂ was about 9 and 3 times higher than those of g-C₃N₄ and SnS₂ photocatalysts, respectively. The superoxide and hydroxyl radicals were the main reactive species in the photocatalytic degradation with a Z-scheme charge transfer mechanism. The g-C₃N₄/SnS₂ nanocomposite was found to be remarkably stable after three consecutive cycles of MB degradation.     

Novel g-C3N4 nanosheets/CDs/BiOCl photocatalysts with exceptional activity under visible light

We fabricated novel ternary nanocomposites through integration of C-dots (carbon dots), BiOCl, and nanosheets of graphitic carbon nitride (g-C₃N₄ nanosheets) by a cost-effective route. The fabricated photocatalysts were subsequently characterized by XRD, EDX, TEM, HRTEM, XPS, FT-IR, UV-vis DRS, TGA, BET, and PL methods to gain their structure, purity, morphology, optical, textural, and thermal properties. In addition, the degradation intermediates were identified by gas chromatography-mass spectroscopy (GC-MS). Photocatalytic performance of the synthesized samples was studied by photodegradations of three cationic (RhB, MB, and fuchsine), one anionic (MO) dyes, one colorless (phenol) pollutant and removal of an inorganic pollutant (Cr(VI)) under visible light. It was revealed that the ternary nanocomposite with loading 20% of BiOCl illustrated superlative performances in the selected photocatalytic reactions compared with the corresponding bare and binary photocatalysts. Visible-light photocatalytic activity of the g-C₃N₄ nanosheets/CDs/BiOCl (20%) nanocomposite was 42.6, 27.8, 24.8, 20.2, and 15.9 times higher than the pure g-C₃N₄ for removal of RhB, MB, MO, fuchsine, and phenol, respectively. Likewise, the ternary photocatalyst showed enhanced activity of 15.3 times relative to the g-C₃N₄ in photoreduction of Cr(VI). Moreover, the ternary nanocomposite exhibited excellent chemical stability and recyclability after five cycles. Finally, the mechanism for improved photocatalytic performance was discussed based on the band potential positions.     

Efficient photocatalytic hydrogen production using an NH4TiOF3/TiO2/g-C3N4 composite with a 3D camellia-like Z-scheme heterojunction structure

Photocatalysis is one of the most promising ways to realize artificial photosynthesis. The biologically inspired photocatalysts with 3D flower-like structures have attracted much attention. In this study, an effective method for the synthesis of composite photocatalytic material, NH₄TiOF₃/TiO₂/g-C₃N₄, with a 3D camellia-like structure, was developed. The 3D hierarchical structure of the composite material enabled multiple refractions and reflections of light within the catalyst, which greatly improved the efficiency of the sunlight harvesting. The combination of NH₄TiOF₃ and TiO₂ also effectively reduced the electron-hole recombination in the g-C₃N₄. To evaluate its photocatalytic performance, the prepared nanostructured composite materials were tested for the water-splitting with simulated sunlight. It showed the hydrogen evolution at the rate of 3.6 mmol/g/h, which is 4.0 times faster than that from the pure g-C₃N₄. The composite materials exhibited excellent cycling stability. The detailed mechanism of the Z-scheme heterojunction was also discussed. The proposed synthesis route for the creation of 3D flower-like hierarchical composites provides a new effective technique for developing efficient, active, and stable composite photocatalysts for hydrogen production.     

Novel spindle-shaped nanoporous TiO2 coupled graphitic g-C3N4 nanosheets with enhanced visible-light photocatalytic activity

Highly efficient visible-light-driven heterojunction photocatalysts, spindle-shaped nanoporous TiO₂ coupled with graphitic g-C₃N₄ nanosheets have been synthesized by a facile one-step solvothermal method. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption analysis and UV–vis diffuse reflectance spectrometry (DRS), proving a successful modification of TiO₂ with g-C₃N₄. The results showed spindle-shaped nanoporous TiO₂ microspheres with a uniform diameter of about 200 nm dispersed uniformly on the surface of graphitic g-C₃N₄ nanosheets. The g-C₃N₄/TiO₂ hybrid materials exhibited higher photocatalytic activity than either pure g-C₃N₄ or nanoporous TiO₂ towards degradation of typical rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under visible light (>420 nm), which can be largely ascribed to the increased light absorption, larger BET surface area and higher efficient separation of photogenerated electron–hole pairs due to the formation of heterostructure. In addition, the possible transferred and separated behavior of electron–hole pairs and photocatalytic mechanisms on basis of the experimental results are also proposed in detail.     

Construction of g-C3N4 nanotube/Ag3PO4 S-scheme heterojunction for enhanced photocatalytic oxygen generation

Heterojunction engineering is considered as a hopeful approach to ameliorate the separation of photogenerated carriers of photocatalysts, realizing efficient water-splitting performance. In this study, an organic-inorganic S-scheme of a one-dimensional g-C₃N₄ nanotube (TCN)/Ag₃PO₄ photocatalytic system with high photocatalytic water oxidation activity was designed by coupling g-C₃N₄ nanotubes over Ag₃PO₄ particles through a chemical coprecipitation method. The TCN/Ag₃PO₄ heterojunction demonstrated excellent photocatalytic O₂ production with an O₂ evolution rate of up to 370.2 μmol·L^?1·h^?1. X-ray photoelectron spectroscopy analysis showed that electron migration between TCN and Ag₃PO₄ led to the formation of an internal electric field pointing from TCN to Ag₃PO₄, which drove the S-scheme charge transfer mode between TCN and Ag₃PO₄. Accordingly, the TCN/Ag₃PO₄ heterojunction possessed fast charge separation and high redox ability, leading to high photoactivity and photostability. This research provides a new strategy for fabricating highly efficient inorganic-organic S-scheme photocatalysts for O₂ production.     

Preparation of exposed (001) facets TiO2/Ti3C2 MXene and performance of near infrared light photodegradation

The (001)TiO₂/Ti₃C₂ MXene heterojunction photocatalyst was prepared with the hydrothermal oxidation method by using the two-dimensional Ti₃C₂ MXene as the substrate. The formation of TiO₂ surface heterojunctions, Schottky junctions at the interface between (001) facets TiO₂ and Ti₃C₂ MXene, and the local surface plasmon resonance effect of plasma Ti₃C₂ MXene combine together to promote the effective separation of electrons and holes after photoexcitation. After 150 min of near infrared light irradiation and sunlight irradiation, the degradation rates of tetracycline by (001)TiO₂/Ti₃C₂ MXene photocatalyst are 28.63% and 52.74%, respectively, with near infrared light and full spectrum degradation characteristics. Our work is expected to provide a valuable reference for the design of MXene based full spectrum photocatalysts.     

Rice spike-like g-C3N4/TiO2 heterojunctions with tight-binding interface by using sodium titanate ultralong nanotube as precursor and template

A novel rice spike-like g-C₃N₄/TiO₂ nanowire heterojunctions are fabricated by hydrothermal treating Na₂Ti₃O₇ ultralong nanotubes in the presence of g-C₃N₄. The presence of g-C₃N₄ promotes the hydrolysis of Na₂Ti₃O₇ ultralong nanotubes. The partially replaced O of TiO₂ by N from g-C₃N₄ leads to the formation of a tight-binding interface between one dimensional TiO₂ and two dimensional g-C₃N₄, which is crucial for fast and effective transfer of photogenerated electrons in heterostructured photocatalysts. As a result, the g-C₃N₄/TiO₂ nanowire heterojunctions exhibit excellent visible-light photocatalytic activity. The kinetic constant (k) of g-C₃N₄/TiO₂ (0.024?min^?1) for degradation of methylene blue under visible light irradiation is 1.85 and 4 times than that of pure g-C₃N₄ and P25, respectively.     

Visible-light-driven Ni3FeN/g-C3N4 Z-scheme heterostructure for remarkable photocatalytic water splitting

It is very essential to grow efficient and abundant photocatalysts for overall water cracking to produce hydrogen. Ni₃FeN nanosheets were synthesized by combining simple sol–gel and calcining methods using urea as nitrogen source. A heterostructure was constructed between Ni₃FeN and g-C₃N₄ to enhance the absorption capacity of visible light. The reformed Z-scheme Ni₃FeN/g-C₃N₄ heterojunction exhibited an excellent visible-light photocatalytic activity. The average hydrogen evolution rate of 5 wt% Ni₃FeN/g-C₃N₄ composite is 528.7 μmol h⁻¹ g⁻¹ due to the Z-scheme Ni₃FeN/g-C₃N₄ junction, which promotes the separation of photogenerated e⁻/h⁺. Interestingly, the average H₂ production of Ni₃FeN/g-C₃N₄ is nearly 8.3 and 3.6 times higher than that of Fe₄N/g-C₃N₄ and Ni₄N/g-C₃N₄, respectively, indicating that bimetallic nitrides as cocatalysts are more conducive to enhancing the performance of photocatalysts. Importantly, the Ni₃FeN/g-C₃N₄ composite exhibited good cycle stability, and the hydrogen production performance hardly changed after four cycle experiments. Furthermore, photoluminescence, electrochemical impedance spectroscopy, and transient photocurrent response show that Ni₃FeN/g-C₃N₄ heterojunction improves the separation efficiency of photoinduced e⁻/h⁺. This work provides a feasibility of the cocatalyst Ni₃FeN for use in photocatalytic hydrogen production.