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The design and development of efficient nitride photocatalysts have attracted much attention. Herein, two-dimensional mesoporous Ta 3 N 5 is successfully synthesized through a simple sol-gel process with filter paper as a biological template and a combination of vacuum nitriding reactions. The prepared Ta 3 N 5 shows a wide light response range up to the near infrared (NIR) region due to the nitrogen vacancies generated from substitution of N3− for O2− ions during vacuum nitridation. Significantly, such a narrow bandgap (∼1.99 eV) still satisfies the redox potential of water splitting in thermodynamics. The experimental results show that the Ta 3 N 5 photocatalyst exhibits an enhanced hydrogen production rate of 34.6 μmol h−1 g−1, which is 3.9 and 2.1 times higher than that of Ta 2 O 5 and partial nitridation of Ta 2 O 5 (N–Ta 2 O 5), respectively. This enhanced photocatalytic performance could be attributed to the high specific surface area to provide reactive active sites, substitution of N3− for O2− ions to optimize the band structure, and special two-dimensional mesoporous structure to shorten the charge transfer distance. This work provides a new perspective for the preparation of two-dimensional nitride materials by a biological template method combining vacuum nitriding with enhanced photocatalytic performance. Two-dimensional mesoporous Ta 3 N 5 is synthesized by a simple sol-gel process with filter paper as a biological template and vacuum nitriding reaction, leading to an efficient photocatalytic performance. [Display omitted] • Two-dimensional mesoporous Ta 3 N 5 was prepared by a biological template. • The prepared Ta 3 N 5 shows a wide light response range up to the near infrared region. • The special two-dimensional structure shortens the charge transfer distance. • The Ta 3 N 5 photocatalyst shows a superior hydrogen production performance. [ABSTRACT FROM AUTHOR]

The simultaneous production of hydrogen and biomass-based chemicals from biomass-derived feedstock aqueous solutions via photocatalysis is appealing because no additional sacrificial agent is needed. However, limited success has been achieved. This paper reports efficient nori-shaped carbon nitride-based photocatalysts with potassium/oxygen co-doping and cyano group introduction for efficient conversion of biomass-derived monosaccharides to produce lactic acid and hydrogen simultaneously. The obtained photocatalyst has an adjustable bandgap, fast migration/separation rate of photo-generated carriers and displays excellent photocatalytic performance with respect to xylose conversion (∼95.0%), lactic acid selectivity (90.5%) and hydrogen generation (∼33 380 μmol g−1 h−1) in the presence of visible light. The h+, ˙OH, ˙O2− and 1O2 drive xylose conversion and lactic acid production. For biomass-derived pentoses and hexoses, the reaction system also exhibits excellent photocatalytic activity of lactic acid selectivity and hydrogen generation; the reported photocatalyst has excellent reusability. This paper provides a new perspective for hydrogen generation and biorefineries via a photocatalyst. [ABSTRACT FROM AUTHOR]

In this paper, a novel pristine carbon nitride (np-CN) with hollow capsule-like morphology was facilely prepared by the thermal polymerization of melamine and cyanuric chloride at 550 1C in air for 4 h. Then, modified carbon nitride (CN-P4mg) micro-flakes with zigzag edges were synthesized by the copolymerization of melamine, cyanuric chloride, and triaminotriphenylamine with a mass fraction of 0.13%. Analysis of the microstructure, surface state, porosity, and optoelectronic properties of the two samples indicates that CN-P4mg has a larger specific surface area and a lower bandgap than np-CN. Under visible light, CN-P4mg displays enhanced photocatalytic performance for the generation of hydrogen compared to that of np-CN and bulk graphite carbon nitride (g-C3N4). The photocatalytic hydrogen evolution rate of CN-P4mg reaches 16897.3 mmol g-1 h-1, which is 1.84 times that of np-CN and 72 times that of bulk g-C3N4. The experimental results confirm that the addition of triaminotriphenylamine provides a modified design for developing metal-free carbon nitride derivatives and a new route to study efficient photocatalytic materials. [ABSTRACT FROM AUTHOR]

N-rich precursors govern the thermal polymerization formation of graphitic carbon nitride (g-C 3 N 4) based catalysts towards enhanced photocatalytic performance. In this paper, Cu components were introduced in superior thin g-C 3 N 4 nanosheets using the thermal polymerization copper acetate and bulk g-C 3 N 4 created by different precursors including melamine, dicyandiamide, and thiourea, such as melamine-g-C 3 N 4 (MCN), dicyandiamide-g-C 3 N 4 (DCN), and thiourea-g-C 3 N 4 (TCN). The performance of Cu-g-C 3 N 4 nanosheets depended strongly on the precursors of bulk g-C 3 N 4 samples. The well-developed Cu nanoparticles with clear lattice fringes were observed in the sample prepared using MCN (sample Cu-MCN) while the crystallinity of Cu nanoparticles became worse in the sample prepared using DCN (sample Cu-DCN). Interestingly, Cu clusters were homogeneously distributed in superior thin g-C 3 N 4 nanosheets in the case of using TCN (sample Cu-TCN) because of S components in thiourea affected the thermal polymerization. The photocatalytic activity of Cu-TCN was drastically improved compared with other Cu-g-C 3 N 4 samples. The photocatalytic hydrogen production rate of Cu-TCN with 1% of Cu components was 4035.6 μmol g-1 h-1. Cycle stability test indicated that sample Cu-TCN revealed high stability, in which the H 2 generation rate was retained 95% of their initial value after 5 cycles. These results supply efficient approaches for the study and application of g-C 3 N 4 based photocatalysts. • Cu components introduced in g-C 3 N 4 nanosheets using bulk g-C 3 N 4 created by different precursors. • Precursors (melamine, dicyandiamide, and thiourea) affect the activity of Cu-g-C 3 N 4 nanosheets. • Cu distribution in g-C 3 N 4 nanosheets depended on the thermal polymerization of precursors. • Cu clusters distributed in g-C 3 N 4 nanosheets created using thiourea revealed the best performance. [ABSTRACT FROM AUTHOR]

Developing highly active and stable non-noble-metal cocatalyst-decorated semiconductors is desirable for the practical application of photocatalysis, which remains an open question. Herein, we report transition-metal nitride (Ni3FeN) loaded cadmium sulfide (CdS) nanorods prepared through a simple hydrothermal method and surface treatment with NH3. The as-prepared photocatalyst Ni3FeN (3 wt%)/CdS showed a hydrogen evolution rate of 4.6 mmol g−1 h−1, which was 23.8 and 6.8 fold higher than those of CdS and Pt (1 wt%)/CdS, respectively. The Ni3FeN/CdS sample exhibited remarkable stability for seven consecutive cycles of photocatalytic tests lasting 21 hours. It was confirmed through Kelvin probe measurements that a Schottky junction between Ni3FeN and CdS gave rise to the inhibited recombination of photogenerated carriers, which benefited the photocatalytic HER performance. [ABSTRACT FROM AUTHOR]

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C3N4)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C3N4 in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. [ABSTRACT FROM AUTHOR]

Elemental doping is an effective and attractive method for improving the photocatalytic performance. Here we synthesized three types of O-doped carbon nitride nanofibers (ACN, CCN, and LCN) through a one-pot simple solvothermal process by using L -arginine, L -cysteine and L -lysine as O dopants into pristine carbon nitride nanofibers (CNF). The three O-doped samples exhibited enhanced light harvesting capacity and satisfactory O2 adsorption and activation ability, which is beneficial for the following H2O2 generation process. The photocatalytic H2O2 generation rates of the optimal ACN, CCN, and LCN samples are 156.9, 166.2 and 107.2 μmol g−1 h−1, which are higher than that of pristine CNF (72.3 μmol g−1 h−1). Especially, CCN shows an apparent quantum efficiency of 4.66% at 420 nm. The results of photocurrent measurements and photoluminescence spectra indicate that the charge carrier recombination was effectively inhibited in the O-doped samples. Our research provides an effective and environmentally friendly strategy to improve the H2O2 generation performance by using common compounds in human life. [ABSTRACT FROM AUTHOR]

Summary: There are various methods to produce hydrogen from water splitting as a substitute energy resource for fossil fuels in accordance with the global environmental crisis. Among these, water photocatalysis is considered one of the most renewable and sustainable processes simulated the solar energy utilized system in nature. During a half century, different kinds of photocatalysts were developed to convert photon energy into chemical energy to induce redox potential under visible light irradiation condition. In the beginning step, semiconductor materials, such as transition metal oxides, were explored extensively to use as a photocatalyst for hydrogen generation. However, semiconductor has limitations to act as an effective photocatalyst for water splitting due to the large band gap and recombination of charge carriers. Therefore, several kinds of modifications of structure or components have been studied to design visible light active photocatalysts for water splitting to generate hydrogen. Their performance was improved substantially by adding a noble metal or sensitizer to adjust the band gap and reduce the recombination of photoinduced charge carriers. Considering solar light‐induced photocatalytic hydrogen generation, various visible light active photocatalysts have been derived from carbon chain organic compounds and lattice crystals. This review classifies the visible light active photocatalysts as follows: (a) structural and chemical components of modified graphitic carbon nitride (g‐C3N4), (b) exfoliated perovskites, and (c) π‐bond conjugated polymers to produce hydrogen from water splitting. The hydrogen evolution efficiency of photocatalysts shows a great difference under visible light (λ > 400 nm) irradiation according to the three‐dimensional structure and electron transfer pathway. This is because the capability of restricting the recombination of photoinduced charge carriers and the band gap between the valence band and the conduction band of photocatalysts is dependent on the morphology and electrostatic interactions among components. This paper reviews visible light photocatalysts, that is, g‐C3N4 based materials, layered perovskites, and conjugated polymers, to provide integrated insight into photocatalytic water splitting to obtain hydrogen. [ABSTRACT FROM AUTHOR]

Adjusting the interlayer structure of carbon nitride is expected to adjust its physicochemical properties, thereby enhancing photocatalytic activity. In this paper, alkaline metal ion-intercalated carbon nitride was prepared by molten salt co-pyrolysis. Alkali metal ions acted as mediators to provide a new migration path for the photogenerated electrons of g-C3N4. The intercalation of K+ and Na+ reduced the bandgap value of carbon nitride, expanded the visible light absorption range, and promoted the separation and migration of charge carriers. As a result, the hydrogen production rate of DCN1 reached 500 μmol g−1 h−1, which was 10 times than that of pristine g-C3N4. Experimental and theoretical methods were used to explain the improvement of photocatalytic efficiency after K+ and Na+ were intercalated into the interlayer of g-C3N4. Our work provided a new idea for the design of high-efficiency hydrogen evolution photocatalysts via intercalation method. [ABSTRACT FROM AUTHOR]

[Display omitted] Construction of Z-scheme heterojunctions has been considered one superb method in promoting solar-assisted charge carrier separation of carbon-based materials to achieve efficient utilization of solar energy in hydrogen production and CO 2 reduction. One interesting concept in nanofabrication that has become trend recent years is nanoarchitectonics. A heterostructure photocatalyst constructed based on the idea of nanoarchitectonics using the combination of g-C 3 N 4 , metal and an additional semiconducting nanocomposite is investigated in this paper. Z-scheme tungsten oxide incorporated copper modified graphitic carbon nitride (WO x /Cu-g-C 3 N 4) heterostructures are fabricated via immobilization of WO x on Cu nanoparticles modified superior thin g-C 3 N 4 nanosheets. Mechano-chemical pre-reaction and a two-step high-temperature thermal polymerization process are the keys in attaining homogeneous distribution of Cu nanoparticles in g-C 3 N 4 nanosheets. The horizontal growth of homogeneously distributed WO x nanobelts on Cu modified g-C 3 N 4 (Cu-g-C 3 N 4) base via solvothermal synthesis is achieved. The photocatalytic performances of the heterostructures are evaluated through water splitting and CO 2 photoreduction measurements in full solar spectrum irradiation condition. The presence of Cu nanoparticles in the composite system improves charge transport between g-C 3 N 4 and WO x and thus enhances the photocatalytic performances (H 2 generation and CO 2 photoreduction) of the composite material, while the presence of WO x nanocomposites enhances light absorption of the composite material in the near infrared range. The synthesized heterostructure with optimized WO x to Cu-g-C 3 N 4 ratio and in case of no co-catalyst addition exhibits enhanced photocatalytic H 2 evolution (4560 μmolg-1h−1) as well as excellent CO 2 reduction rate (5.89 μmolg-1h−1 for CO generation). [ABSTRACT FROM AUTHOR]

Atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters (Ni 6 NCs) supported on g-C 3 N 4 nanosheets were constructed to enhance the photocatalytic hydrogen evolution performances. [Display omitted] Much effort has been devoted to improving the photocatalytic capacity of graphitic carbon nitride (g-C 3 N 4). In this paper, we reported the successful synthesis of a hybrid photocatalyst with superb photocatalytic hydrogen production activity through decorating atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters on g-C 3 N 4 nanosheets (labeled as Ni 6 /g-C 3 N 4) at room temperature. Zeta potential experiments demonstrated that the electrostatic interaction between Ni 6 and g-C 3 N 4 led to the formation of Ni 6 /g-C 3 N 4. The photocatalytic measurements revealed that the 5 %-Ni 6 /g-C 3 N 4 prepared with the original mass ratio of m(Ni 6)/m(g-C 3 N 4) = 1/20 exhibited the strongest hydrogen production activity. In the system with triethanolamine (TEOA) as the sacrifice agent, the visible-light hydrogen production rate reached up to 5.87 mmol h−1 g−1, approximately 290 times higher than that of pure g-C 3 N 4 (0.02 mmol h−1 g−1). Density functional theory (DFT) calculations testified that the above significant enhancement of photocatalytic hydrogen evolution of the hybrid photocatalyst arose from the photogenerated electrons transfer from Ni 6 to g-C 3 N 4. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) carried out from electrocatalysis of water splitting is playing a major role in the production of green and clean hydrogen. In this paper, we report on the synthesis of graphitic carbon nitride on nickel hydroxide (g-C 3 N 4 /Ni(OH) 2) nanocomposites by a simple ultrasonication method. The characterizations include the XRD, Raman, FESEM and electrochemical studies to analyze the performance of the as developed material over hydrogen evolution reaction. The morphological analysis shows that the aggregated interconnected g-C 3 N 4 /Ni(OH) 2 (GCN/NH) nanocomposites with an average particle size of ∼20 nm. These GCN/NH nanocomposites exhibit the lowest overpotential of 341 mV at 10 mA/cm2 which is smaller than that of the pristine Ni(OH) 2 nanosheets at 367 mV. Further, the Tafel slope for GCN/NH nanocomposites reveals a lower value of 131 mV/dec. As a result, g-C 3 N 4 decorated sheet-like β-Ni(OH) 2 exhibits the potential hydrogen evolution in alkaline KOH solution. Excitingly, the as developed hybrid β-Ni(OH) 2 nanocomposites show superior electrocatalytic behaviour during the hydrogen evolution reaction and also improve the catalytic stability than pure nanosheets. From these observations, one can say that this g-C 3 N 4 /Ni(OH) 2 nanocomposite electrocatalyst can play a splendid role in future energy technology. • One step synthesis of β-Ni(OH) 2 and g-C 3 N 4 /Ni(OH) 2 via sonochemical method. • Prepared electrodes were characterized for the electrocatalytic HER studies. • The electrochemically active surface area of nanocomposite is higher than that of the pristine. • The overpotential of the g-C 3 N 4 /Ni(OH) 2 nanocomposite is lower than that of the pristine Ni(OH) 2. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride is considered as an ideal semiconductor material for photocatalytic hydrogen evolution due to its suitable energy band structure, durability and environmental friendliness. To further improve the catalytic performance of g-C3N4, nickel phosphide-loaded one-dimensional tubular carbon nitride (Ni2P/TCN) was prepared by thermal polymerization and photo deposition. The beneficial effect of the one-dimensional tubular structure on hydrogen generation was mainly attributed to its larger specific surface area (increased light absorption) as well as the linear movement of the carriers, which reduced their diffusion distance to the surface and facilitated the separation of photogenerated carriers. The loading of Ni2P co-catalyst improved the visible light utilization efficiency and enabled the migration of photogenerated electrons towards Ni2P, which ultimately reacted with the enhanced adsorbed H+ on the Ni2P surface to facilitate the photocatalytic hydrogen evolution process. This study provides new clues for the further development of efficient, environmentally friendly and low-cost g-C3N4 catalysts. [ABSTRACT FROM AUTHOR]

Booming of photocatalytic water splitting technology (PWST) opens a new avenue for the sustainable synthesis of high‐value‐added hydrogenated and oxidized fine chemicals, in which the design of efficient semiconductors for the in‐situ and synergistic utilization of photogenerated redox centers are key roles. Herein, a porous polymeric carbon nitride (PPCN) with a crystalline backbone was constructed for visible light‐induced photocatalytic hydrogen generation by photoexcited electrons, followed by in‐situ utilization for olefin hydrogenation. Simultaneously, various alcohols were selectively transformed to valuable aldehydes or ketones by photoexcited holes. The porosity of PPCN provided it with a large surface area and a short transfer path for photogenerated carriers from the bulk to the surface, and the crystalline structure facilitated photogenerated charge transfer and separation, thus enhancing the overall photocatalytic performance. High reactivity and selectivity, good functionality tolerance, and broad reaction scope were achieved by this concerted photocatalysis system. The results contribute to the development of highly efficient semiconductor photocatalysts and synergistic redox reaction systems based on PWST for high‐value‐added fine chemical production. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure evolution of polymeric carbon nitride was investigated and Au ions was used to improve its photocatalytic efficiency. Their structures were investigated by FT-IR, XPS, XRD, SEM and TEM. Their specific surface area and aperture distribution were measured by BET. Meanwhile, the energy band structure and electron-hole separation efficiency were analyzed by UV–Vis and PL spectroscopy. In addition, the photocatalytic performance of the photocatalysts was assessed by photocatalytic degradation of RhB and photocatalytic hydrogen evolution. The results showed that 600-PCN possessed the best photocatalytic performance, with a degradation rate of 46.92 % in 150 min. What's more, the degradation rate of RhB solution by 2 % Au/PCN reached 47.88 %, which was 2.17 times higher than that of 550-PCN (22.01 %). During the degradation process, h+ oxidatively degrade RhB. The hydrogen production rate of 2 % Au/PCN was about 11.658 μmol/g/h, which was 41.23 times higher than that of 550-PCN (0.282 μmol/g/h). • PCN is basically formed at 500 oC, but 600-PCN has better photocatalytic performance. • 2.0 % Au/PCN showed the best hydrogen production performance, with a hydrogen production rate of about 11.658 μmol/g/h. • 2.0 % Au/PCN showed the highest degradation rate of RhB solution with 47.88 %, and the main active substance is h+. [ABSTRACT FROM AUTHOR]

Two dimensional (2D)/2D heterostructures with much interface is advantage to improve the transfer of photogenerated carriers. In this paper, SnS 2 nanosheets were horizontally grown on superior thin graphic carbon nitride (g-C 3 N 4) nanosheets to construct 2D/2D heterostructures with enhanced photocatalytic performance. The g-C 3 N 4 nanosheets (CN) were obtained by a two-step thermal polymerization at 600 and 700 °C. the growth of SnS 2 nanosheets was then carried out using a solvothermal synthesis. Preparation parameters including temperature, reaction time, and precursor components were tested to get optimized SnS 2 /g-C 3 N 4 composite sample 8SnS 2 -CN. A Z-scheme mechanism was proposed for the discussion of photocatalytic process. The degradation test of Rhodamine B (Rh B) indicated that the degradation rate of Rh B using sample 8SnS 2 -CN was twice quick compared with g-C 3 N 4 nanosheets, in which Rh B degradation was completed within 15 min. The photocatalytic hydrogen production rate of sample 8SnS 2 -CN was about 6 times that that of sample CN, which is 1818.75 μmol g−1 L−1. Enhanced photocatalytic performance is ascribed to SnS 2 deposited to form well-developed interface which improved the separation and transfer of photogenerated carriers. In addition, the growth of SnS 2 was also expended the photo adsorption. [Display omitted] [ABSTRACT FROM AUTHOR]

Typical non-metallic semiconductor carbon nitride (CN) has enormous potential in the field of photocatalysis, but the easy recombination of the photo-generated charges severely limits its practical applications. Herein, oxygen-doped and nitrogen vacancy co-modified carbon nitride (ODCN) was prepared by simple reduction and oxidation treatments. The experimental results show that the modified CN can effectively enhance the photocatalytic activity, indicating that there is a synergy between oxygen doping and nitrogen vacancy. The photocatalytic hydrogen generation rate of ODCN is 364 μmol g−1 h−1, which is higher than that of bulk CN, nitrogen vacancy-modified carbon nitride (DCN) and oxygen-doped modified carbon nitride (OCN). As a consequence, our work provides a neoteric idea for the co-modification of carbon nitride by a variety of methods, which can significantly improve the photocatalytic activity of carbon nitride and is expected to be applied in practical applications. [ABSTRACT FROM AUTHOR]

Solar energy can generate hydrogen via water splitting, which could decrease the environmental pollutions. During the photocatalytic hydrogen generation, some semiconductors can improve efficiencies. Recently, graphitic carbon nitride (g-C3N4) attracts interests due to visible light response. However, pristine g-C3N4 exhibits low photocatalytic activity. In this work, Au nanorods (Au NRs) were prepared via the colloidal seed-mediated approach, which assembled different structures by L-Cysteine (L-Cys). Meanwhile, the g-C3N4 was synthesized by means of thermal condensation of melamine. Based on this, we reports some photocatalysts by combining different Au NRs structures (random, aligned and aggregated) with g-C3N4. The hydrogen generation rates of different Au NR/g-C3N4 composites are 30.1 μmol h−1 g−1 (aligned), 44.5 μmol h−1 g−1 (random) and 46.9 μmol h−1 g−1 (aggregated), respectively. Interestingly, the hydrogen evolution rates are proportional to the surface plasmon resonance (SPR) enhancements of different Au NRs structures. The random and aggregated structures with some vertical Au NRs in contact with g-C3N4, can provide a better circuit for continuous flow of hot charge carriers. Nevertheless, horizontally aligned Au NRs reduce the Schottky barrier between Au NRs and g-C3N4, which enhances the back electrons and thus slow down the hydrogen generation. Our work reveals the effective Au/semiconductor photocatalysts to fabricate the vertically oriented Au NR layer contact with the semiconductor surface. This represents one of the future directions in this field. The preparation of different photocatalysts based on pristine g-C3N4 and aligned Au NR structures with g-C3N4. Our present work reveals the effective Au/semiconductor photocatalysts are to fabricate a highly vertically oriented Au NR layer with the ends of the Au NRs in direct contact with the semiconductor surface. This represents one of the future directions in this field. [ABSTRACT FROM AUTHOR]

Structural modulation of graphitic carbon nitride (g‐C3N4) remains a major challenge in rational catalyst design for artificial photosynthesis of valuable chemicals. Herein, a cellulose nanofiber (CNF) assisted polymerization is utilized to prepare 1D holey g‐C3N4 nanorods (HCN) with nitrogen vacancies and oxygen dopants for photochemical synthesis of lactic acid via monosaccharide photooxidation. The HCN exhibits a remarkable yield of 75.5% for lactic acid from a wide assortment of sugars such as hexose (C5) to pentose (C6), together with an excellent hydrogen production rate of 2.8 mmol h−1 g−1. Mechanistic studies confirm the rapid generation of superoxide radical is responsible for the superior activity, enjoying the synergetic effect between nitrogen vacancies and oxygen dopants. This work provides new directions for the design of green and efficient photocatalysts for biomass upgrading. [ABSTRACT FROM AUTHOR]

Black phosphorus (BP) and heptazine-based crystalline carbon nitride (KPHI) composite photocatalysts were synthesized by molten salt and ultrasound-assisted liquid phase exfoliation methods. The structure, morphology and optical properties of the as-prepared BP/KPHI composites were evaluated by various characterization techniques. In addition, the photocatalytic performance of BP/KPHI composites for hydrogen production was investigated. The photocatalytic activity of BP/KPHI composite catalysts could be modulated by changing the loading mass ratio of BP. The BP/KPHI composite photocatalyst with a mass ratio of 10% exhibited the highest photocatalytic activity with the hydrogen production rate of 4.3 mmol g−1 h−1, about three times higher than that of pristine KPHI. Benefiting from the advantages of simplicity, rapidity, high yield and good controllability, this nanocomposite photocatalyst has the potential to serve as an excellent photocatalytic material for solar energy conversion. [ABSTRACT FROM AUTHOR]

O2 adsorption and activation are important factors in H2O2 production. Here, polymeric carbon nitride (PCN) with K was prepared using a hydrothermal method. Modified PCN with strong Lewis acidic–basic sites is favorable for O2 adsorption and activation from air, and could quickly supplement the oxygen adsorbed from the air for the production of a high H2O2 yield (2102.11 μmol g−1), and the yield is 42 times higher than that of pristine PCN in the atmosphere. The apparent quantum yields (AQYs) are 3.87% and 2.62% at 385 and 420 nm in the atmosphere, respectively. [ABSTRACT FROM AUTHOR]

Exfoliated graphitic carbon nitride (ex-g-CN) was synthesized and loaded with non-noble metals (Ni, Cu, and Co). The synthesized catalysts were tested for hydrogen production using a 300-W Xe lamp equipped with a 395 nm cutoff filter. A noncommercial double-walled quartz-glass reactor irradiated from the side was used with a 1 g/L catalyst in 20 mL of a 10 vol% triethanolamine aqueous solution. For preliminary screening, the metal-loaded ex-g-CN was synthesized using the incipient wetness impregnation method. The highest hydrogen production was observed on the Ni-loaded ex-g-CN, which was selected to assess the impact of the synthesis method on hydrogen production. Ni-loaded ex-g-CN was synthesized using different synthesis methods: incipient wetness impregnation, colloidal deposition, and precipitation deposition. The catalysts were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption using the Brunauer–Emmett–Teller method, and transmission electron microscopy. The Ni-loaded ex-g-CN synthesized using the colloidal method performed best with a hydrogen production rate of 43.6 µmol h−1 g−1. By contrast, the catalysts synthesized using the impregnation and precipitation methods were less active, with 28.2 and 10.1 µmol h−1 g−1, respectively. The hydrogen production performance of the suspended catalyst (440 µmol m−2 g−1) showed to be superior to that of the corresponding immobilized catalyst (236 µmol m−2 g−1). [ABSTRACT FROM AUTHOR]

In this paper, a visible light-driven polymeric carbon nitride (PCN)/(Pt)/nano-spherical MoS 2 photocatalysts was prepared using a self-assembly method. The structure of photocatalysts was explored by FT-IR, XPS, XRD, BET, SEM and TEM. Meanwhile, the energy band structure and electron hole separation efficiency were also analyzed by UV–Vis and PL spectra. In addition, the photocatalytic performance of photocatalysts were tested by photocatalytic degradation of Rhodamine B and photocatalytic hydrogen evolution. The results showed that PCN/2.0%MoS 2 showed the best photocatalytic performance, and the degradation rate of Rhodamine B could reach 98.39% within 150 min. Besides, the introduction of Pt nanoparticles significantly improved the photocatalytic activity. The degradation rate of Rhodamine B reached 100% within 150 min, and the rate of photocatalytic hydrogen production of PCN/Pt/MoS 2 system was increased by 21.3% over the PCN/2.0%MoS 2 system. The separation mechanism of electron and hole is Z-scheme mechanism and the main active substances for photocatalytic degradation were · O 2 − and h+. [Display omitted] • The catalyst is prepared by self-assembly. • Pt promotes the formation of carriers. • The transportation of carriers is Z-scheme. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (C3N4) was synthesised from melamine at 550 °C for 4 h in the argon atmosphere and then was reheated for 1–3 h at 500 °C in argon. Two band gaps of 2.04 eV and 2.47 eV were observed in all the synthetized materials. Based on the results of elemental and photoluminescence analyses, the lower band gap was found to be caused by the formation of vacancies. Specific surface areas of the synthetized materials were 15–18 m2g−1 indicating that no thermal exfoliation occurred. The photocatalytic activity of these materials was tested for hydrogen generation. The best photocatalyst showed 3 times higher performance (1547 μmol/g) than bulk C3N4 synthetized in the air (547 μmol/g). This higher activity was explained by the presence of carbon (VC) and nitrogen (VN) vacancies grouped in their big complexes 2VC + 2VN (observed by positron annihilation spectroscopy). The effect of an inert gas on the synthesis of C3N4 was demonstrated using Graham´s law of ammonia diffusion. This study showed that the synthesis of C3N4 from nitrogen-rich precursors in the argon atmosphere led to the formation of vacancy complexes beneficial for hydrogen generation, which was not referred so far. [ABSTRACT FROM AUTHOR]

P-doped graphitic carbon nitride tubes (P-CNTS) with different P concentrations were successfully fabricated via a pre-hydrothermal in combination with a calcination process under a nitrogen atmosphere. The as-prepared samples exhibited excellent photocatalytic performance with a hydrogen production rate (HPR) of 2749.3 μmol g−1 h−1, which was 17.5 and 6.6 times higher than that of the bulk graphitic carbon nitride (CNB) and graphitic carbon nitride tube (CNT). The structural and textural properties of the P-CNT samples were well-investigated via a series of characterization methods. Compared with the bulk g-C3N4, the tubular structure of the doped samples was provided with a larger specific surface area (SSA) and a relatively rough interior. Besides the above, surface defects were formed due to the doping, which could act as more active sites for the hydrogen production reaction. In addition, the introduction of the P element could effectively adjust the band-gap, strengthen the harvest of visible-light, and boost the effective separation of photogenerated charges. More interestingly, these findings can open up a novel prospect for the enhancement of the photocatalytic performance of the modified g-C3N4. [ABSTRACT FROM AUTHOR]

The present work reports a facile strategy to develop L-arginine mediated Zn doped graphitic carbon nitride (g-C3N4) and its enhanced photocatalytic activity. The physicochemical properties of Zn-doped g-C3N4 were studied extensively by XPS, UV–Vis, XRD, SEM and BET analysis. The studied properties of the photocatalyst were then correlated with its photocatalytic hydrogen production rates. Zn doping was evidenced by the presence of Zn-N peak from high-resolution core level XPS spectral analysis. Photocatalytic hydrogen evolution experiments revealed that, upon Zn doping, the hydrogen production rate of g-C3N4 was increased from 34.6 to 78.7 µmol/g.h, i.e. 2.3 times more. The enhancement in the photocatalytic properties after Zn doping was addressed by estimating changes in the positions of conduction band minimum and valence band maximum through XPS valence band spectral analysis. [ABSTRACT FROM AUTHOR]

• The recent advances of graphitic carbon nitride for the hydrogen production and photocatalytic water splitting were summarized. • The drawbacks and the solution to overcome it have been discussed. • The advanced strategies to increase the performance of graphitic carbon nitride have been systematically discussed. The future energy crisis and environmental degradation can only mitigate by harvesting solar energy into renewable, safe, economical and clean technology like water splitting. The graphitic carbon nitride has an attractive band structure, good chemical stability, earth-abundant and significantly easily fabricated which makes an application for the generation of hydrogen by water splitting. In this paper, we try to critically focus on the current progress and future development of the different strategies of water splitting using graphitic carbon nitride (g-C 3 N 4) for hydrogen generation. In this context, we discuss recent strategies like metal and non-metal doping (electronic structure), morphology tuning (geometric structuring), use of mediators (Z-scheme technology), defects engineering, plasmonic materials, dye-sensitization, perovskite oxides, carbon nitrides, carbon dots, metal organic framework, and a bimetallic cocatalyst. Finally, we summarize the recent advances and future developments of g-C 3 N 4 bases photocatalysis. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitrides (CNs) have been identified as attractive photocatalysts owing to their comparatively low cost and facile modification of their electronic structure. Herein, we report an effective strategy to tune the surface oxygen species linking site of polymeric CN, achieving more effective charge separation. A high photocatalytic hydrogen production rate of approximately 10225 μmol h−1 g−1 under visible light irradiation (λ>420 nm) and an impressive apparent quantum efficiency (AQE) of 5.7 % at 430 nm were recorded. Specifically, thermal treatment under a H2 and then an air atmosphere allowed the oxygen species linker on the surface of CN to be changed from −C=O to N=C−OH and then −C−O−C−, resulting in unbalanced charge distribution, which significantly enhanced the photogenerated charge separation, further contributing to the high hydrogen production performance. This linker regulation strategy may provide a new path for the development of highly efficient photocatalysts. [ABSTRACT FROM AUTHOR]

Replacing the high theoretical potential of anodic water decomposition (oxygen evolution reaction) with the low theoretical potential of urea oxidation reaction (UOR) is an urgent need for hydrogen energy storage and conversion. Cobalt nitride nanoflakes, high-performance bifunctional catalysts supported on nickel foam (Co 5. 4 7 N NF/NF), were synthesized by hydrothermal and calcination method. The morphology and composition of the catalyst were studied by XRD, XPS, SEM, TEM, HRTEM and elemental analysis. In order to conduct electrochemical performance and stability, a two-electrode electrolyzer composed of Co 5. 4 7 N NF/NF as both anode and cathode materials is constructed (Co 5. 4 7 N NF/ NF | | Co 5. 4 7 N NF/NF). Only a voltage of 1.687 V is needed to complete 100 mA ⋅ cm − 2 . It is much lower than the voltage of Pt/ C | | IrO 2 (1.816 V), because of which it is believed that this work provides a valuable route for the design of inexpensive and efficient urea electrolysis-assisted hydrogen generation. A non-noble metal bifunctional catalyst (Co5.47N NS/NF) was synthesized by simple, low-cost hydrothermal and calcination methods for urea electrolysis-assisted hydrogen production. Co5.47N NS/NF with unique nanosheets structure was used as both anode and cathode materials, which exhibits better activity and stability than precious metal catalysts. This implies that it is commercially viable. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) has been widely studied as a photocatalyst for the splitting of water to produce hydrogen. In order to solve the problems of limited number of active sites and serious recombination rate of charge-carriers, noble metals are needed as cocatalysts. Here, we selectively anchored Pt nanoparticles (NPs) to specific nitrogen species on the surface of g-C3N4 via heat treatment in argon–hydrogen gas mixture, thus achieving g-C3N4 photocatalyst anchored by highly dispersed homogeneous Pt NPs with the co-existed metallic Pt0 and Pt2+ species. The synergistic effect of highly dispersed metallic Pt0 and Pt2+ species makes the catalyst exhibit excellent photocatalytic performance. Under the full-spectrum solar light irradiation, the photocatalytic hydrogen production rate of the photocatalyst is up to 18.67 mmol·g−1·h−1, which is 5.1 times of the catalyst prepared by non-selective deposition of Pt NPs. [ABSTRACT FROM AUTHOR]

Solar-to-fuel conversion is an innovative concept for green energy, attracting many researchers to explore them. Solar-driven photocatalysts have become an essential solution to provide valuable chemicals like hydrogen, hydrocarbon, and ammonia. For sustainable stability under solar irradiation, titanium dioxide is regarded as an acceptable candidate, further showing excellent photocatalytic activity. Incorporating the photo-sensitizers, including noble metal nanoparticles and polymeric carbon-based material, can improve its photoresponse and facilitate the electron transfer and collection. In this study, we synthesized the graphitic carbon nitride (g-C3N4) nanosheet incorporated with high crystalline TiO2 nanofibers (NF) as 1D/2D heterostructure catalyst for photocatalytic water splitting. The microstructure, optical absorption, crystal structure, charge carrier dynamics, and specific surface area were characterized systematically. The low bandgap of 2D g-C3N4 nanosheets (NS) as a sensitizer improves the specific surface area and photo-response in the visible region as the incorporated amount increases. Because of the band structure difference between TiO2 and g-C3N4, constructing the heterojunction formation, the superior separation of electron-hole is observed. The detection of reactive oxygen species and photo-assisted Kelvin probe microscopy are conducted to investigates the possible charge migration. The highest photocatalytic hydrogen production rate of Pd/TiO2/g-C3N4 achieves 11.62 mmol·h−1·g−1 under xenon lamp irradiation. [ABSTRACT FROM AUTHOR]

Mein Motto ist: Rette die Welt und diene der Gesellschaft'. 3 "Mesoporous Carbon Nitrides: Synthesis, Functionalization, and Applications": K. S. Lakhi, D.-H. Park, K. Al-Bahily, W. Cha, B. Viswanathan, J.-H. Choy, A. Vinu, Chem. Soc. 4 "Gold Nanoparticles Embedded in a Nanoporous Carbon Nitride Stabilizer for Highly Efficient Three-Component Coupling Reaction": K. K. R. Datta, B. V. Subba Reddy, K. Ariga, A. Vinu, Angew. [Extracted from the article]

Metal-free carbon materials, with tuned surface chemical and electronic properties, hold great potential for the hydrogen evolution reaction (HER). We designed and synthesized a CN/BG hybrid electrocatalytic system with a porous and active graphite carbon nitride (CN) layer on boron-doped graphene (BG). A porous CN layer on graphene could provide exposed defects and edges that act as active sites for proton adsorption and reduction. The composition, structure, surface electronics, and chemical properties of this CN/BG hybrid system were tuned to obtain excellent HER activity and stability. Detailed surface chemical, morphological, and structural analyses demonstrated the synergetic effect arising from the electronic interaction between CN and BG, which contributed to the enhanced electrocatalytic performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen-doped crystalline carbon nitride (CCNO) was successfully synthesized. • Pharmaceuticals and personal care products (PPCPs) were readily degraded by CCNO. • Hydrogen fuel was recovered from photocatalytic degradation of PPCPs by CCNO. • An energy-recovering wastewater treatment process using solar energy is proposed. Degrading organic pollutants while generating hydrogen from water splitting is an ideal application of photocatalysis. Herein, we presented an efficient photocatalyst, oxygen-doped crystalline carbon nitride, to power the degradation of various kinds of pharmaceuticals and personal care products and the simultaneous hydrogen production. The highest efficiency was achieved in treating the simulated wastewater containing naproxen (NPX), with the H 2 evolution rate of 819.1 µmol/g/h and the NPX degradation efficiency of 92 % upon visible light irradiation. Experimental and computational results suggested that the doped oxygen atoms thermodynamically favored the generation of hydroxyl peroxide for pollutant degradation and lowered the energy barrier of H 2 O reduction to produce hydrogen fuel. Most importantly, the catalysts functioned well in the natural aquatic environment including sea water, sewage water, river water, and well water. This study provides fundamental insights into photocatalytic water treatment with simultaneous hydrogen production, indicating an energy-recovering approach for wastewater treatment. [ABSTRACT FROM AUTHOR]