g-C 3 N 4 photocatalysis is a safe and green approach for H 2 O 2 production, but the activity of pristine g-C 3 N 4 photocatalysts is unsatisfactory. At present, most of the modifications on g-C 3 N 4 photocatalysts for H 2 O 2 production have focused on thermodynamic processes, few have considered the kinetic aspects. Herein, the surface N-hydroxymethylation of g-C 3 N 4 photocatalysts for the efficient kinetic production of H 2 O 2 is reported. Through the reaction of formaldehyde with the amino moieties (-NH 2 ) on the g-C 3 N 4 surface, N-hydroxymethyls groups (-NH-CH 2 -OH) are introduced on typical g-C 3 N 4 photocatalysts. Relative to the pristine g-C 3 N 4 photocatalysts, the modified g-C 3 N 4 photocatalysts have over 1280% higher activity for H 2 O 2 production in pure water system, and impressive solar-to-chemical conversion efficiency. The experimental investigations and theoretical calculations reveal that the introduction of -NH-CH 2 -OH on the g-C 3 N 4 photocatalysts does not change their morphology, light absorption intensity and edges, band positions, charge separation and transfer properties, but markedly improved the H 2 O dehydrogenation and O 2 adsorption properties of g-C 3 N 4 . As a result, the reduction kinetics of O 2 to H 2 O 2 on the g-C 3 N 4 photocatalysts with -NH-CH 2 -OH is more energetically favorable. This work provides a useful reference and inspiration to achieve the effective modification of g-C 3 N 4 or other metal-free photocatalysts from the kinetic perspective.

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The thermal-condensation method is widely used for the synthesis of K-doped g-C3N4 photocatalysts, but the presence of organic byproducts in the resultant products is often overlooked in previous reports. Here, we demonstrated the universal presence of organic byproducts in K-doped g-C3N4 synthesized by typical thermal condensation of KOH/melamine, KOH/dicyandiamide, or KOH/urea. Taking the K-doped g-C3N4 photocatalysis for the degradation of dimethyl phthalate as an example, the negative influence of the organic byproducts on K-doped g-C3N4 photocatalysis was confirmed. Specifically, the organic byproducts can be gradually dissolved into the photocatalytic system of K-doped g-C3N4 as new and stable pollutants. Based on the solubility investigations on the byproducts in several solvents, hot-water washing was demonstrated to be a relatively effective approach to remove the organic byproducts from K-doped g-C3N4. The formation of organic byproducts during the synthesis of K-doped g-C3N4 could be ascribed to the fact that the presence of K salts in melamine, dicyandiamide, or urea molecules results in their insufficient thermal condensation into expected g-C3N4. The present work provides objective information about the K-doped g-C3N4 photocatalysts and reminds researchers about the influence of the organic byproducts on the applications of the other impurity-doped g-C3N4 photocatalysts.

The development of BiVO4-based heterojunction photoanodes with thermodynamic and kinetic advantages is one of the breakthrough directions to fulfill the potential of BiVO4 for solar water splitting. Here, we designed and investigated a Cu3Mo2O9/BiVO4 heterojunction film photoanode that consisted of p-type Cu3Mo2O9 nanoparticles and an n-type BiVO4 film for water oxidation. Compared to the BiVO4 film, the resultant Cu3Mo2O9/BiVO4 heterojunction film shows better activity and stability during water oxidation owing to the synergistic effect of the p–n heterojunction and Cu3Mo2O9 cocatalysis. Specifically, the formed p–n heterojunctions of Cu3Mo2O9/BiVO4 are thermodynamically favorable to the separation and transfer of photoexcited holes–electrons, which result in a higher activity of the Cu3Mo2O9/BiVO4 photoanode for water oxidation. Meanwhile, the Cu3Mo2O9 electrocatalysis could be initiated by the photoexcited holes of BiVO4, which can enhance the water oxidation kinetics and stability of the Cu3Mo2O9/BiVO4 film photoanode. Our study provides a reference to design BiVO4-based heterojunction photoanodes with integrated advantages in thermodynamics and kinetics for water splitting.

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The menace of antimicrobial resistance continues to increase and hence the need to discover new antibiotics, especially alternative and effective sources such as hybrid organic-inorganic, organic-organic materials, and other combinations. In this study, an antimicrobial hybrid supra-nano material was prepared by the bi-titration synthesis method of chitosan (CS) and ZnAl layered double hydroxide. Fourier-transform infrared spectrometer (FTIR), thermogravimetric and differential thermal gravimetric (TGA/DTG), ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses indicated that the ZnAl/CS hybrid exhibited low crystallinity with high thermal stability. The results of ZnAl/CS characterization showed the characteristic properties of the individual components ZnAl and CS, indicating a successful preparation of the ZnAl/CS hybrid. The antibacterial tests revealed that the ZnAl/CS hybrid possessed an enhanced antimicrobial effect against both Escherichia coli (E. coli, MTCC 739) and Penicilliumcyclopium (P. cyclopium, AS 3.4513). Under the central composite design (CCD) of the response surface methodology (RSM) tool, the parameters of the hybrid synthesis reaction were optimized and the result obtained was as follows: reaction pH was 11.3, reagent Zn/Al ratio was 3.27, and chitosan concentration was 1.07 g/L. After optimization, it was found that the antibacterial activity of ZnAl/CS was strengthened against E. coli as evidenced by a widening of the inhibition zone of about 41.6%. The antibacterial activity of ZnAl/CS was mainly due to the reactivation of the antibacterial activity of CS associated with the release of Zn2+ and Al3+ metal ions in addition to ZnO, Al2O3, and ZnAl2O4 compounds resulting from the method of preparation.

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The structures and properties of dibenzo [b,d]thiophene (DBT) based alternating donor-acceptor conjugated oligomers, in which thieno[3,4-b]pyrazine (TP), thieno[3,4-b]thiadiazole (TD), and [1,2,5]thiadiazolo[3,4-e]thieno [3,4-b]pyrazine (TTP) as acceptors, and their periodic polymers were investigated by the density function theory (DFT) at the B3LYP/6-31G(d) level. The bond length, electron density at bond critical points (BCPs) and nucleusindependent chemical shift (NICS) are analyzed and correlated with the conductive properties. NICS shows that the conjugation degree is increased with main chain extension. Research results show the conductive ability of compounds with 1:2 D-A ratio is better than that with 1:1 D-A ratio. The reorganization energies and energy bands also are considered. The results suggest that (BTDDBT) n and (BTPDDBT) n have small reorganization energy (0.163 and 0.152 eV, respectively) and quite low energy gap (0.73 and 0.56 eV, respectively), which indicate that they may be potential organic conductive materials.