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The development of nonpyrolytic catalysts featuring precisely defined active sites represents an effective strategy for investigating the fundamental relationship between the catalytic activity of oxygen reduction reaction (ORR) catalysts and their local coordination environments. In this study, we have synthesized a series of model electrocatalysts with well‐defined CoN4 centers and nonplanar symmetric coordination structures. These catalysts were prepared by a sequential process involving the chelation of cobalt salts and 1,10‐phenanthroline‐based ligands with various substituent groups (phen(X), where X=OH, CH3, H, Br, Cl) onto covalent triazine frameworks (CTFs). By modulating the electron‐donating or electron‐withdrawing properties of the substituent groups on the phen‐based ligands, the electron density surrounding the CoN4 centers was effectively controlled. Our results demonstrated a direct correlation between the catalytic activity of the CoN4 centers and the electron‐donating ability of the substituent group on the phenanthroline ligands. Notably, the catalyst denoted as BCTF−Co‐phen(OH), featuring the electron‐donating OH group, exhibited the highest ORR catalytic activity. This custom‐crafted catalyst achieved a remarkable half‐wave potential of up to 0.80 V vs. RHE and an impressive turnover frequency (TOF) value of 47.4×10−3 Hz at 0.80 V vs. RHE in an alkaline environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen vacancy-mediated carbon nitride (DCNA) modified by deep eutectic solvents for the first time. • DCNA shows 4.93-fold improvement in atrazine removal. • Hole (h+) was found to be the most dominant active species for photocatalytic degradation of atrazine. • N–H of atrazine the side chain is the main adsorption site of DCNA. • The wheat growth toxicity test significantly reduced the degradation byproducts' toxicity. Metal-free photocatalysts like graphitic carbon nitride (g-C 3 N 4) can have their electronic structures altered by vacancy defect engineering, greatly increasing their catalytic activity. Here, we have synthesized nitrogen vacancy mediated carbon nitride (DCNA) modified by deep eutectic solvents for the first time, DCNA showed 4.93-fold improvement compared to pristine g-C 3 N 4 towards photocatalytic degradation of atrazine (ATZ). Besides, we have revealed the role of photogenic holes as the main active species for the photocatalytic degradation of ATZ. This improvement is attributed to the increased nitrogen vacancy, which increases the adsorption of N–H on the ATZ side chain, accelerates the process of photoelectron and hole separation, and allows more holes to participate in ATZ degradation. Moreover, the wheat growth toxicity test significantly reduced the degradation byproducts' toxicity. This study provides an effective method for preparing environmentally friendly metal-free photocatalysts with high catalytic performance. [ABSTRACT FROM AUTHOR]

Heterojunction is an effectively construction to improve the photocatalytic activity due to the excellent photo-induced carrier separation efficiency. In this paper, g-C 3 N 4 /Bi 4 O 5 I 2 heterojunction was prepared and characterized by X-ray diffraction patterns (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic data showed that g-C 3 N 4 /Bi 4 O 5 I 2 heterojunction had higher activity than pure g-C 3 N 4 and Bi 4 O 5 I 2 . At an optimal ratio of 1.0 mol% (11.4 wt% of Bi 4 O 5 I 2 ), g-C 3 N 4 /Bi 4 O 5 I 2 photocatalyst showed the highest photocatalytic reduction activity for CO 2 conversion with 45.6 μmol h −1 g −1 CO generation. Photocurrent and electrochemical impedance (EIS) spectroscopy revealed that higher photo-induced carrier separation efficiency of g-C 3 N 4 /Bi 4 O 5 I 2 . Z-scheme charge transfer mode was proved by I 3 − /I − redox mediator existence and superoxide radical (O 2 − ) and hydroxyl radical ( OH) quantification experiments. [ABSTRACT FROM AUTHOR]

Two dimension layered BiOX (X = Cl, Br, I) semiconductor nanomaterials are very important photocatalysts. Our previous work showed that thickness-ultrathin and bismuth-rich strategies are excellent methods to improve the visible-light-driven (VLD) photocatalytic reduction activity of BiOX. In this study, thickness-ultrathin and bismuth-rich strategies were ingenuously combined to enhance the photocatalytic performance of the photocatalyst, via a glycerol precursor route, Bi 4 O 5 Br 2 microsphere assembled by ultrathin nanosheets was synthesized and characterized by X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), time-resolved PL spectra and UV–vis diffuse reflectance spectra (DRS). The thickness of Bi 4 O 5 Br 2 ultrathin nanosheets was about 3.7 nm, which was much thinner than the common BiOBr nanosheets (65 nm). Due to the thickness-ultrathin and bismuth-rich strategies, the synthesized Bi 4 O 5 Br 2 sample displayed a higher photocatalytic reduction activity of CO 2 conversion than BiOBr and ultrathin BiOBr under visible-light irradiation. More importantly, we found that thickness-ultrathin and bismuth-rich strategies played different roles. Thickness-ultrathin strategy only can increase the CO generation while bismuth-rich strategy only can increase the CH 4 generation for photoreduction of CO 2 . [ABSTRACT FROM AUTHOR]

Highlights: [•] BiOBr-g-C3N4 was synthesized by a one-step chemical bath method at low temperature. [•] BiOBr-g-C3N4 showed much higher visible-light-driven (VLD) photocatalytic activity. [•] The interreaction between BiOBr and g-C3N4 is a kind of facet coupling between BiOBr-{001} and g-C3N4-{002}. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO)-BiOCl hybrid materials were prepared by a novel benzyl alcohol route. The formation of uniform RGO-BiOCl hybrids was attributed to the interaction of introduced graphene oxide and BiOCl, which resulted in a selective growth of BiOCl along (110) orientation. The RGO-BiOCl hybrids showed both enhanced visible-light and ultraviolet light photocatalytic activities compared to nano-BiOCl with similar particle size. In particular, the first-order kinetic constant ( k) of Rhodamine B on the optimal RGO (0.73 %)-BiOCl hybrid was 2.5 times that on bare nano-BiOCl under visible-light irradiation. For RGO-BiOCl hybrids, RGO probably acted as a photosensitizer in photocatalytic reaction and resulted in the improved visible-light photocatalytic performance. However, RGO was an excellent electron transfer and inhibited the recombination of electron-hole pairs on BiOCl under ultraviolet light. [ABSTRACT FROM AUTHOR]

Abstract: Anatase TiO2 crystals with {101}–{001} and {010}–{001} two facets coexistence were synthesized by (NH4)2TiF6 acting as titanium and fluorine sources and the photocatalytic activity of the samples were investigated. The replacement of {101} by {010} facets inhibits the photocatalytic activity of anatase TiO2. The mechanism was examined by photoluminescence spectrum, time-resolved photoluminescence spectra, field emission scanning electron microscope (FESEM) images of selected deposition of Ag, surface atoms structures and electronic band structures of anatase TiO2 facets. The results demonstrated that photoinduced charge transfer properties between {101} facets and {001} facets resulted in the efficient charge separation. Replacing {101} by {010}, the charge transfer mechanism was altered and the photoinduced electron–hole pairs cannot be separated well. The photocatalytic activity of it has thus been inhibited. [Copyright &y& Elsevier]

In this paper, gallium oxide (Ga 2 O 3 ) was modified by in situ silver (Ag) to improve the photocatalytic activity for hydrogen (H 2 ) evolution. The photocatalysts Ga 2 O 3 and Ag/Ga 2 O 3 were synthesized via electrospinning and calcination, and characterized by X-ray diffraction patterns (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS). It is observed that the 1% Ag/Ga 2 O 3 had higher activity than that of the pure Ga 2 O 3 for photocatalytic H 2 evolution. Photoluminescence spectra (PL) and transient photocurrent analysis indicated that the high separation efficiency of photo-generated carriers of Ag/Ga 2 O 3 resulted in the high photocatalytic H 2 evolution. [ABSTRACT FROM AUTHOR]

A pyridinic-N dominated carbon spheres is successfully developed via a rational solvothermal and subsequent pyrolysis strategy. Thanks to its abundant and controllable pyridinic-N active centers and large specific surface area, the obtained N/N-CS can readily work as an efficient oxygen reduction electrocatalyst in high performance metal-air battery. [Display omitted] • A pyridinic-N dominated carbon spheres (N/N-CS) is fabricated by a simple yet efficient solvothermal-pyrolysis-conversion strategy. • The N/N-CS exhibits excellent oxygen reduction reaction (ORR) electrocatalytic activities with an ultrahigh half-wave potential (E 1/2 = 0.865 V vs. RHE) and great methanol tolerance. • The optimal electrocatalyst can be used as air cathode material for high-performance zinc-air battery. • The self-assembled zinc-air battery exhibits good discharge property, with a power density of 148 mW cm−2, outperforming commercial Pt/C (127 mW cm−2). The intelligent design of non-metallic catalysts with high-performance and long-term stability towards oxygen reduction reaction (ORR) is essentially required for green and sustainable energy conversion systems. Optimizing carbon nanomaterials with abundant and uniformly distributed nitrogen (N)-type active sites provide more advantages for boosting the ORR. However, designing catalysts with well-defined N-doping active sites is extremely challenging using the current methods/techniques. Herein, we report a rational solvothermal strategy to synthesize covalent triazine polymers (CTPs), which act as ideal "all in one" precursors to fabricate N-doped non-metallic catalyst via subsequent pyrolysis. Due to abundant and precisely-constructed pyridinic-N active sites, the newly-realized N-doped carbon spheres (N/N-CS) catalyst exhibits superb catalytic activity for the ORR with a high half-wave potential (E 1/2 = 0.865 V vs. RHE), excellent tolerance to methanol and great long-term performance. Impressively, while being utilized as cathode material in primary Zn-air batteries, the N/N-CS electrode performs a superior peak power density (∼148 mW cm−2) to that of commercial Pt/C electrocatalyst (∼123 mW cm−2). This work expands an innovative and high-efficiency method for synthesizing non-metallic electrocatalysts with precisely-controlled active sites offering remarkable catalytic ability towards various energy conversion reactions. [ABSTRACT FROM AUTHOR]