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Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Constructing a Z-scheme heterojunction with enhanced photocatalytic hydrogen evolution for graphitic carbon nitride-based (g-C3N4) composites is challenging because integrating g-C3N4 with other semiconductors, without specific band structure design, typically results in type I or type II heterojunctions. These heterojunctions have lower redox ability and limited enhancement in photocatalysis. Herein, we select highly crystalline carbon nitride (HCCN) as a proof-of-concept substrate. For the first time, we develop a AgBr nanosphere/HCCN composite photocatalyst that features an all -solid -state direct Z-scheme heterojunction for visible-light photocatalytic hydrogen evolution. The electron transfer mechanism is initially studied from the band structures and Fermi levels of HCCN and AgBr. It is subsequently confirmed by X-ray photoelectron spectroscopy (XPS), and electron microscopy. The close heterojunction contact and the built-in electron field of the Z-scheme heterojunction promote the migration and separation of photogenerated electrons and holes in the composite photocatalyst. Due to the redistribution of charge carriers, the photocatalyst shows superior redox capability and a markedly enhanced hydrogen evolution performance compared to its individual components. Combining all the advantages, AgBr nanosphere/HCCN reached an apparent quantum efficiency (AQE) of 6 % under the illumination of 410 nm, which is 4 times higher than that of the single HCCN component.

Carbon nitride (CN) has attracted intensive attention as a visible light photocatalyst, but the rapid recombination of photogenerated charge carriers limits its photocatalytic activity. Herein, we develop a new strategy to construct both homojunction and ohmic junction into CN via selectively introducing metallized CN (MCN), which leads to rapid separation and transfer of photogenerated charge carriers. The polymerization of urea in the presence of KOH creates CN homojunction with amino and cyano groups. The subsequent molten salt treatment induces a new type of cyano-terminated CN that can be converted to MCN through photodoping, forming homojunction and ohmic contact coexisting CN (HOCN). The formed HOCN photocatalyst exhibits a high photocatalytic H-2 evolution rate of 18.5 mmol.g(-1).h(-1) under visible light irradiation, 45-fold higher than that of bulk CN. This strategy provides a new idea for designing ohmic contact between semiconductor and metal, and realizing efficient photocatalysis by improving charge separation and transfer.

The direct hybridization of Pt and g-C3N4 generally forms a Schottky barrier between the two components, which unavoidably hinders the migration of photogenerated electrons from g-C3N4 to the Pt cocatalyst. Herein, we report the first efficient allochroic Pt/g-C3N4 photocatalyst that can form an ohmic contact through photoconversion of semiconducting g-C3N4 to metalloid, accompanied with the charge carrier storage and photocatalyst color change, which is proved experimentally and theoretically. Through intermittent exposure of Pt/gC3N4 photocatalyst to air for a few minutes during photocatalysis, the photocatalyst shows the highest hydrogen evolution performances. The ohmic contacts greatly promote the electron transfer from the semiconducting gC3N4 to the Pt cocatalyst driven by the built-in electric field. In addition, the mechanism for the photocatalyst deactivation and activation is presented. The compositional tuning of the allochroic g-C3N4 through light irradiation and exposure to air can control over the photocatalytic activity and long-term stability for hydrogen evolution. This report for the first time unveils the deactivation and regeneration mechanisms of SCN.

The direct hybridization of Pt and g-C3N4 generally forms a Schottky barrier between the two components, which unavoidably hinders the migration of photogenerated electrons from g-C3N4 to the Pt cocatalyst. Herein, we report the first efficient allochroic Pt/g-C3N4 photocatalyst that can form an ohmic contact through photoconversion of semiconducting g-C3N4 to metalloid, accompanied with the charge carrier storage and photocatalyst color change, which is proved experimentally and theoretically. Through intermittent exposure of Pt/gC3N4 photocatalyst to air for a few minutes during photocatalysis, the photocatalyst shows the highest hydrogen evolution performances. The ohmic contacts greatly promote the electron transfer from the semiconducting gC3N4 to the Pt cocatalyst driven by the built-in electric field. In addition, the mechanism for the photocatalyst deactivation and activation is presented. The compositional tuning of the allochroic g-C3N4 through light irradiation and exposure to air can control over the photocatalytic activity and long-term stability for hydrogen evolution. This report for the first time unveils the deactivation and regeneration mechanisms of SCN.

The direct hybridization of Pt and g-C3N4 generally forms a Schottky barrier between the two components, which unavoidably hinders the migration of photogenerated electrons from g-C3N4 to the Pt cocatalyst. Herein, we report the first efficient allochroic Pt/g-C3N4 photocatalyst that can form an ohmic contact through photoconversion of semiconducting g-C3N4 to metalloid, accompanied with the charge carrier storage and photocatalyst color change, which is proved experimentally and theoretically. Through intermittent exposure of Pt/gC3N4 photocatalyst to air for a few minutes during photocatalysis, the photocatalyst shows the highest hydrogen evolution performances. The ohmic contacts greatly promote the electron transfer from the semiconducting gC3N4 to the Pt cocatalyst driven by the built-in electric field. In addition, the mechanism for the photocatalyst deactivation and activation is presented. The compositional tuning of the allochroic g-C3N4 through light irradiation and exposure to air can control over the photocatalytic activity and long-term stability for hydrogen evolution. This report for the first time unveils the deactivation and regeneration mechanisms of SCN.

The direct hybridization of Pt and g-C3N4 generally forms a Schottky barrier between the two components, which unavoidably hinders the migration of photogenerated electrons from g-C3N4 to the Pt cocatalyst. Herein, we report the first efficient allochroic Pt/g-C3N4 photocatalyst that can form an ohmic contact through photoconversion of semiconducting g-C3N4 to metalloid, accompanied with the charge carrier storage and photocatalyst color change, which is proved experimentally and theoretically. Through intermittent exposure of Pt/gC3N4 photocatalyst to air for a few minutes during photocatalysis, the photocatalyst shows the highest hydrogen evolution performances. The ohmic contacts greatly promote the electron transfer from the semiconducting gC3N4 to the Pt cocatalyst driven by the built-in electric field. In addition, the mechanism for the photocatalyst deactivation and activation is presented. The compositional tuning of the allochroic g-C3N4 through light irradiation and exposure to air can control over the photocatalytic activity and long-term stability for hydrogen evolution. This report for the first time unveils the deactivation and regeneration mechanisms of SCN.

The direct hybridization of Pt and g-C3N4 generally forms a Schottky barrier between the two components, which unavoidably hinders the migration of photogenerated electrons from g-C3N4 to the Pt cocatalyst. Herein, we report the first efficient allochroic Pt/g-C3N4 photocatalyst that can form an ohmic contact through photoconversion of semiconducting g-C3N4 to metalloid, accompanied with the charge carrier storage and photocatalyst color change, which is proved experimentally and theoretically. Through intermittent exposure of Pt/gC3N4 photocatalyst to air for a few minutes during photocatalysis, the photocatalyst shows the highest hydrogen evolution performances. The ohmic contacts greatly promote the electron transfer from the semiconducting gC3N4 to the Pt cocatalyst driven by the built-in electric field. In addition, the mechanism for the photocatalyst deactivation and activation is presented. The compositional tuning of the allochroic g-C3N4 through light irradiation and exposure to air can control over the photocatalytic activity and long-term stability for hydrogen evolution. This report for the first time unveils the deactivation and regeneration mechanisms of SCN.

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m2 g-1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g-1 h-1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g-1 h-1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m2 g-1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g-1 h-1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g-1 h-1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m2 g-1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g-1 h-1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g-1 h-1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.

Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.

Labels based on physical unclonable functions (PUFs) have been proven to be some of the most effective anticounterfeiting strategies. However, it is still challenging to develop PUF-based anticounterfeiting labels with low prices, simple manufacturing, and easy authentication. Herein, photochromic PUF labels are fabricated by randomly dispersing highly crystalline carbon nitride (HCCN) particles in poly(vinyl acetate) (PVAc). The color of the PVAc/HCCN films originating from photochromism is used as the first layer of safety, which is verified by the naked eye. The pattern of the randomly distributed HCCN particles within the photochromic area (i.e., the PUF) is used as the second layer of security. The PUF can be read out by any smartphone equipped with a portable objective and then automatically authenticated by computer vision technology. We further prove the accurate and feasible authentication of the prepared PUFs and their application potentials.

Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.

Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.

Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m2 g-1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g-1 h-1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g-1 h-1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.

Cadmium sulfide has attracted wide attention in photocatalytic hydrogen production, due to its appropriate bandgap and band positions. However, high-rate photogenerated electron-hole recombination and few active sites on CdS lead to its low photocatalytic activity. Herein, a PANI/NCPP/CdS (PANI/NiCoP/NiCoPi/CdS) hybrid as a noble metal-free visible light-driven photocatalyst is reported, with metal phosphides, metal phosphates, and polyaniline (PANI) as reduction and oxidation cocatalysts, respectively. This hybrid not only facilitates the charge separation and transfer owing to the formation of heterojunction, but also improves the local concentration of H+ on the surface of catalysts due to the formation of the protonated amine groups on PANI, bene?cial to hydrogen evolution reaction. As a result, the as-prepared photocatalyst could show a high hydrogen evolution rate of 170.3 mmol g(-1) h(-1) and an apparent quantum efficiency of 41.37% at 420 nm, representing one of the best performances of all-CdS-based photocatalysts.

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m2 g-1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g-1 h-1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g-1 h-1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.

Photocatalytic hydrogen production is considered as an ideal approach to solve global energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4) has received extensive consideration due to its facile synthesis, stable physicochemical properties, and easy functionalization. However, the pristine g-C3N4 usually shows unsatisfactory photocatalytic activity due to the limited separation efficiency of photogenerated charge carriers. Generally, introducing semiconductors or co-catalysts to construct geC(3)N(4)-based heterojunction photocatalysts is recognized as an effective method to solve this bottleneck. In this review, the advantages and characteristics of various types of geC(3)N(4)-based heterojunction are analyzed. Subsequently, the recent progress of highly efficient geC(3)N(4)-based heterojunction photocatalysts in the field of photocatalytic water splitting is emphatically introduced. Finally, a vision of future perspectives and challenges of geC(3)N(4)-based heterojunction photocatalysts in hydrogen production are presented. Predictably, this timely review will provide valuable reference for the design of efficient heterojunctions towards photocatalytic water splitting and other photoredox reactions.

Photocatalytic hydrogen production is considered as an ideal approach to solve global energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4) has received extensive consideration due to its facile synthesis, stable physicochemical properties, and easy functionalization. However, the pristine g-C3N4 usually shows unsatisfactory photocatalytic activity due to the limited separation efficiency of photogenerated charge carriers. Generally, introducing semiconductors or co-catalysts to construct geC(3)N(4)-based heterojunction photocatalysts is recognized as an effective method to solve this bottleneck. In this review, the advantages and characteristics of various types of geC(3)N(4)-based heterojunction are analyzed. Subsequently, the recent progress of highly efficient geC(3)N(4)-based heterojunction photocatalysts in the field of photocatalytic water splitting is emphatically introduced. Finally, a vision of future perspectives and challenges of geC(3)N(4)-based heterojunction photocatalysts in hydrogen production are presented. Predictably, this timely review will provide valuable reference for the design of efficient heterojunctions towards photocatalytic water splitting and other photoredox reactions.

Photocatalytic hydrogen production is considered as an ideal approach to solve global energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4) has received extensive consideration due to its facile synthesis, stable physicochemical properties, and easy functionalization. However, the pristine g-C3N4 usually shows unsatisfactory photocatalytic activity due to the limited separation efficiency of photogenerated charge carriers. Generally, introducing semiconductors or co-catalysts to construct geC(3)N(4)-based heterojunction photocatalysts is recognized as an effective method to solve this bottleneck. In this review, the advantages and characteristics of various types of geC(3)N(4)-based heterojunction are analyzed. Subsequently, the recent progress of highly efficient geC(3)N(4)-based heterojunction photocatalysts in the field of photocatalytic water splitting is emphatically introduced. Finally, a vision of future perspectives and challenges of geC(3)N(4)-based heterojunction photocatalysts in hydrogen production are presented. Predictably, this timely review will provide valuable reference for the design of efficient heterojunctions towards photocatalytic water splitting and other photoredox reactions.

Photocatalytic hydrogen production is considered as an ideal approach to solve global energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4) has received extensive consideration due to its facile synthesis, stable physicochemical properties, and easy functionalization. However, the pristine g-C3N4 usually shows unsatisfactory photocatalytic activity due to the limited separation efficiency of photogenerated charge carriers. Generally, introducing semiconductors or co-catalysts to construct geC(3)N(4)-based heterojunction photocatalysts is recognized as an effective method to solve this bottleneck. In this review, the advantages and characteristics of various types of geC(3)N(4)-based heterojunction are analyzed. Subsequently, the recent progress of highly efficient geC(3)N(4)-based heterojunction photocatalysts in the field of photocatalytic water splitting is emphatically introduced. Finally, a vision of future perspectives and challenges of geC(3)N(4)-based heterojunction photocatalysts in hydrogen production are presented. Predictably, this timely review will provide valuable reference for the design of efficient heterojunctions towards photocatalytic water splitting and other photoredox reactions.

Photocatalytic hydrogen production is considered as an ideal approach to solve global energy crisis and environmental pollution. Graphitic carbon nitride (g-C3N4) has received extensive consideration due to its facile synthesis, stable physicochemical properties, and easy functionalization. However, the pristine g-C3N4 usually shows unsatisfactory photocatalytic activity due to the limited separation efficiency of photogenerated charge carriers. Generally, introducing semiconductors or co-catalysts to construct geC(3)N(4)-based heterojunction photocatalysts is recognized as an effective method to solve this bottleneck. In this review, the advantages and characteristics of various types of geC(3)N(4)-based heterojunction are analyzed. Subsequently, the recent progress of highly efficient geC(3)N(4)-based heterojunction photocatalysts in the field of photocatalytic water splitting is emphatically introduced. Finally, a vision of future perspectives and challenges of geC(3)N(4)-based heterojunction photocatalysts in hydrogen production are presented. Predictably, this timely review will provide valuable reference for the design of efficient heterojunctions towards photocatalytic water splitting and other photoredox reactions.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

Modifying the structure of a photocatalyst to tailor its electronic and physicochemical properties is an effective approach for efficient photocatalysis. Herein, we demonstrate that co-doping non-metal (S) and metal (K) atoms into graphitic carbon nitride (g-C3N4) provides excellent visible-light photocatalytic hydrogen production activity of 8.78 mmol g−1 h−1, which is 98 times higher than that of pristine g-C3N4 (0.09 mmol g−1 h−1). The apparent quantum efficiency of the S+K-co-doped g-C3N4 reaches 70 % at 420 nm. This outstanding photocatalytic performance attributed to an increased specific surface area from 6.78 to 74.23 cm3 g−1, which reduced the recombination of photogenerated charge carriers and enhanced conductivity. Various characterizations are undertaken to elucidate the S+K-co-doped g-C3N4 photocatalytic mechanism. Our work not only demonstrates a facile, eco-friendly and scalable strategy for the synthesis of S+K-co-doped g-C3N4 photocatalysts, but also opens a new avenue for the design of co-doped photocatalysts.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

Cadmium sulfide (CdS) as one of the most common visible-light-responsive photocatalysts has been widely investigated for hydrogen generation. However, its low solar-hydrogen conversion efficiency caused by fast carrier recombination and poor catalytic activity hinders its practical applications. To address this issue, we develop a novel and highly efficient nickel-cobalt phosphide and phosphate cocatalyst-modified CdS (NiCoP/CdS/NiCoPi) photocatalyst for hydrogen evolution. The dual-cocatalysts were simultaneously deposited on CdS during one phosphating step by using sodium hypophosphate as the phosphorus source. After the loading of the dual-cocatalysts, the photocurrent of CdS significantly increased, while its electrical impedance and photoluminescence emission dramatically decreased, which indicates the enhancement of charge carrier separation. It was proposed that the NiCoP cocatalyst accepts electrons and promotes hydrogen evolution, while the NiCoPi cocatalyst donates electrons and accelerates the oxidation of sacrificial agents (e.g., lactic acid). Consequently, the visible-light-driven hydrogen evolution of this composite photocatalyst greatly improved. The dual-cocatalyst-modified CdS with a loading content of 5 mol % showed a high hydrogen evolution rate of 80.8 mmol.g(-1).h(-1), which was 202 times higher than that of bare CdS (0.4 mmol.g(-1).h(-1)). This is the highest enhancement factor for metal phosphide-modified CdS photocatalysts. It also exhibited remarkable stability in a continuous photocatalytic test with a total reaction time of 24 h.

A novel configuration of porous ZnO/Sn1-xZnxO2-x, heterojunction nanocatalyst with high photocatalytic activity was successfully synthesized through a simple two-step solvothermal method. Porous Sn1-xZnxO2, was synthesized from Zn2+ and Sn4+ precursors with the Zn/Sn ratio of 2:1 in the absence of alkali, and then intermolecular dehydrolysis led to the formation of heterointerface between Sn1-xZnxO2, and ZnO. The results show that Zn2+ doping exhibits a significant influence on particle size of SnO2 leading to much higher specific surface area and larger band gap, which is in favor of the photocatalytic activity of SnO2 under UV light irradiation. In addition, the formation of ZnO/Sn1-xZnxO2 heterostructure improves the separation of photogenerated electron hole pairs due to the potential difference between Sn1-xZnxO2, and ZnO, which also benefits to photocatalysis. By taking account of them together, these results provide further insight into the synergistic effects of metal ion doping and semiconductor/semiconductor heterostructure on the activity of photocatalysts in environmental remediation applications. (C) 2013 Elsevier B.V. All rights reserved.