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The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts. [ABSTRACT FROM AUTHOR]

Highly effective photocatalysts for the hydrogen‐evolution reaction were developed by conferring the linkers of NH2‐MIL‐125(Ti), a metal–organic framework (MOF) constructed from TiOx clusters and 2‐aminoterephthalic acid (linkers), with active copper centers. This design enables effective transfer of electrons from the linkers to the transient Cu2+/Cu+ centers, leading to 7000‐fold and 27‐fold increase of carrier density and lifetime of photogenerated charges, respectively, as well as high‐rate production of H2 under visible‐light irradiation. This work provides a novel design of a photocatalyst for hydrogen evolution using non‐noble Cu2+/Cu+ as co‐catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H 2 O 2) production from O 2 reduction. Herein, we synthesized the DPCN catalysts possessing nitrogen defects by one-step thermal polymerization of urea in N 2 stream. As compared to the PCN conventionally synthesized in static air, X-ray photoelectrons spectroscopy (XPS) characterization disclosed that there are more pyridinic N defects in the DPCN catalysts, which is attributed to the removal of a proportion of NH 3 released from urea pyrolysis by flowing N 2. UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Mott–Schottky, steady-state and time-resolved photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) characterizations revealed that the introduction of the nitrogen defects narrows down the band gap, improves the density of the photoexcited charge carriers, prolongs the lifetime of the charge carriers, and enhances the charge transfer efficiency. In visible light-driven photocatalytic O 2 reduction to H 2 O 2 , the optimal DPCN catalyst afforded an activity of 4.35 times that of the PCN catalyst and a H 2 O 2 concentration of 2.83 mmol L–1 after 10 h of visible light irradiation. This one-step thermal polymerization approach is valid when replacing N 2 stream with Ar and He streams. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • K and/or P-doped carbon nitrides were synthesized from urea and different salts. • They were evaluated in visible light photocatalytic production of H 2 O 2 from O 2. • The K 2 HPO 4 /GCN (CNKP-10) catalyst produced the highest concentration of H 2 O 2. • K and P were identified to be incorporated into the framework of CNKP-10. • They narrowed down the band gap and enhanced the utility of the charge carriers. Abstract Photocatalytic production of hydrogen peroxide (H 2 O 2) from two-electron reduction of molecular oxygen over semiconductor catalysts under visible light irradiation represents a clean and sustainable strategy to transform solar energy to chemicals. Here we synthesized a series of potassium and/or phosphorus-doped carbon nitride photocatalysts by one-pot thermal polymerization of urea and different sylvites and phosphates. Among them, the K 2 HPO 4 /GCN (CNKP-10) catalyst exhibited the best visible light photocatalytic activity for H 2 O 2 production from molecular oxygen. After 10 h visible light (λ ≥ 420 nm) irradiation, the concentration of H 2 O 2 exceeded 5 mmol l–1 on this catalyst, which is more than five folds of that on the catalyst synthesized by thermal polymerization of urea only (GCN). A combination of bulk and surface characterization techniques confirmed the incorporation of potassium and phosphorus into the framework of GCN, which narrowed down the band gap, raised the conduction band, and enhanced the generation, transmission, and lifetime of the photogenerated charge carriers, thus promoting the visible light photocatalytic production of H 2 O 2 from molecular oxygen. [ABSTRACT FROM AUTHOR]