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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]

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]

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]

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]

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]