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A novel structurally stable 2D-boron nitride material, namely di-BN, is predicted by means of the first-principles simulations. This monolayer BN system is composed of the azo (N N) and diboron (B B) groups. Its in-plane stiffness is close to the monolayer h-BN. Usually, the boron nitride materials are semiconductors with large band gaps. However, the monolayer di-BN possesses a moderate direct band gap of 1.622 eV obtained from our HSE06 calculation. Although the GW correction enlarges the band gap to 2.446 eV, this value is still in the range of the visible light. The detailed investigation of its band arrangement reveals that this material is able to product hydrogen molecules in a photocatalytic water splitting reaction. Furthermore, its charge carrier mobilities are significantly higher than the other popular 2D semiconductors, e.g., MoS 2 and phosphorene. Therefore, this 2D-BN material could have huge application potentials in the electronics and solar energy conversion fields. • A new boron nitride monolayer system, di-BN composed of B B and N N pairs, is proposed. • Unlike the other boron nitride systems with large band gaps, di-BN possesses an optimal direct band gap about 1.622 eV at HSE06 level. • The di-BN is a promising photocatalytic material for hydrogen evolution by water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous cPTA/CN nanorod was prepared by using PTA as both template and adhesive. • In such a nanocomposite, the CN nanolayer forms on the surface of cPTA nanorods. • cPTA/CN degrades 97% RhB in 80 min and 78% tetracycline in 3 h under visible light. • cPTA facilitates the photoinduced carrier separation and afford more active sites. • This study offers a generic method for making nanorod photocatalysts. Solar energy-driven photocatalysis has become a promising green technology to degrade organic pollutants discharged into water environment in recent years. In this study, a kind of novel cPTA/CN nanorod photocatalysts were prepared by using poly(tannic acid) as both template and adhesive, in which the g-C 3 N 4 (CN) nanolayer formed on the surface of carbonized poly(tannic acid) (cPTA) nanorods, similar to the adhesion of marine mussel foot silk protein on the solid surface. The porous cPTA/CN nanorods with about 400 nm in width and 2–4 μm in length can degrade 97% Rhodamine B within 80 min and 78% tetracycline within 3 h under visible light irradiation. Porous cPTA nanorods play an important role for promoting the photocatalytic activity, which can not only accelerate the separation of photogenerated carriers, but also afford more active sites and molecule diffusion channels. This kind of nanocomposite photocatalysts may find broad application potential in the treatment of organic pollutants in aqueous solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low-cost FVC photocatalysts were successfully prepared using two-step hydrothermal method. • The prepared FVC photocatalysts exhibited a narrow bandgap of 2.0 eV and a wide light absorption range of 400 ∼ 700 nm. • Rapid transfer of photogenerated electrons through carbon media in FVC photocatalysts. • CSB, FV, and PMS had synergistic effect on promoting OFX degradation under visible light. • Gradual decrease in the toxicity of OFX intermediates. Biochar is recognized as a good medium for promoting photogenerated charge separation in photocatalysts. In this study, the FeVO 4 /coconut shell biochar (CSB) composites (FVC) were prepared through a cost-effective hydrothermal approach to activate peroxymonosulfate (PMS) for the degradation of ofloxacin (OFX). Incorporated CSB expanded the light absorption range of FVC by approximately 100 nm, and the band gap energy of FVC was reduced to 2.00 eV. Measurements through linear scanning voltammetry (LSV) and current–time (IT) chronoamperometric further confirmed that the accelerated electron transmission rate boosted PMS oxidation, which was attributed to the role of CSB acting as a mediator. Importantly, OFX degradation was significantly boosted by CSB, FV, and PMS synergistically. FVC had a significant OFX degradation efficiency under visible light irradiation (95.2 %) compared to FV (70.9 %), CSB (57.8 %) and PMS (30.5 %). Moreover, the h+, 1O 2 , ·O2–, ·OH, and SO 4 ·− were the main active species, whose degradation pathways were explored and the toxicity of the intermediates was assessed. Furthermore, the as-obtained FVC exhibited a remarkable stability and reusability. This work provides new insights into the mechanism of biochar-mediated charge transfer for antibiotic degradation. [ABSTRACT FROM AUTHOR]

Abstract Graphic carbon nitride (g-C 3 N 4) is a kind of promising organic semiconductor in visible light driven photocatalysis due to its metal free, high physicochemical stability and appealing electronic band structure. In this work, a porous hexagonal-prism g-C 3 N 4 (ACNH) photocatalyst was successfully synthesized via an acetic acid-assisted supramolecular assembly approach followed by calcination. The resulting ACNH materials have a corrugated and closely packed porous structure, which is composed of thin layers about 30 nm in thickness. The specific surface area of ACNH is as high as 67.7 m2 g−1, which is approximately 8-fold of bulk g-C 3 N 4. Moreover, the porous structure induces the red shift of the absorption edge and facilitates the photo-induced charge separation of g-C 3 N 4. Compared to bulk g-C 3 N 4 , the ACNH sample exhibits almost 13-fold improvement for the RhB degradation with the rate constant of 0.053 min−1. This finding suggests that the acid-assisted supramolecular assembly may become a feasible method to synthesize g-C 3 N 4 -based photocatalysts with higher surface area and photocatalytic activity. Graphical abstract Unlabelled Image Highlights • A facile way to synthesize g-C 3 N 4 from supermolecular precursors is proposed. • Porous g-C 3 N 4 hexagonal-prisms with high specific surface were obtained. • Acetic acid serves as pore-forming agent in the formation of porous g-C 3 N 4. • ACNH-3 exhibits almost 13-fold increase in RhB degradation than bulk g-C 3 N 4. [ABSTRACT FROM AUTHOR]