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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]

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]

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]

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]

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]

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]

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]

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]