Search

Herein, well‐crystallized ZnTiO3 particles are first prepared by hydrothermal method. A series of S‐scheme heterojunction photocatalysts of ZnTiO3/g‐C3N4 (referred to as ZTO/CN) with different mass ratios are synthesized by successfully doping ZnTiO3 in g‐C3N4 precursors and loading ZnTiO3 onto g‐C3N4 nanosheets by calcination. It is clearly found that the ZnTiO3 particles are successfully loaded on g‐C3N4 nanosheets by the X‐ray diffractometer, energy‐dispersive X‐ray spectra, and high‐resolution transmission electron microscopy images. Moreover, the specific surface area of 3.0% ZTO/CN is higher than that of pure g‐C3N4. Using triethanolamine as the hole sacrificial agent, the highest CO and H2 yields are achieved in the 3.0% ZTO/CN composite catalyst under the xenon lamp irradiation for 1 h. The generation rates of CO and H2 reach 15.19 and 5.77 μmol g−1 h−1, respectively, which are 2.9 and 4.1 times higher than that of pure g‐C3N4. The CO and H2 yields of the ZTO/CN composite catalyst show a trend of increasing and then decreasing with the increasing of ZnTiO3 content, which is due to the fact that excess ZnTiO3 can lead to a reduction of the effective heterojunction interface between ZnTiO3 and g‐C3N4, decreasing the transfer and separation efficiency of photogenerated electrons and holes and thus reducing the photocatalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new photocatalytic material was forming by self-assembling of V-doped BiOIO 3 and FTCN and introducing of tungsten carbide. • V-BiOIO 3 /g-C 3 N 4 /WC have exhibited high visible-light photodegradation of antibiotic. • The presence of S-type Schottky heterojunction in V-BiOIO 3 /g-C 3 N 4 /WC enhances the degradation efficiency of tetracycline. • Tungsten carbide as a cheap and widely available material has a positive effect on the promotion of photocatalytic industrial process. A novel Schottky heterojunction was obtained by co-calcining fish-scale tubular carbon nitride (FTCN), V-BiOIO 3 and Tungsten carbide (WC) for photocatalytic degradation of tetracycline hydrochloride (TCH). The novel Schottky heterojunction has been analyzed by several characterizations and experiments. The case of photocatalytic degradation was studied for different initial concentrations, electrolyte and pH, respectively. The experiments have indicated that the V-BiOIO 3 /g-C 3 N 4 /WC performed an excellent activity of photocatalytic for TCH degradation (89.0%). In the mechanism analysis, we first deduce that the V-BiO3/FTCN compound belongs to the S-scheme heterojunction photocatalysts based on the properties of the band gap structure, which can effectively suppress recombination of joint carriers. Secondly, the introduction of the cocatalyst WC formed Schottky junction, which could play a role as an electronic library to trap e− and promote the separation of photo-induced carrier and thus maximize the strong oxidation ability of h+. In addition, the introduction of WC could also significantly enhance the optical absorption properties of the composites. This research could provide a new idea for the construction of novel and efficient carbon nitride-based photocatalysts under VSL (visible light), and promote its practical application in environmental remediation. [ABSTRACT FROM AUTHOR]

• Sm3+/Tm3+ co-doped BiVO 4 micro-squares were synthesized. • Sm3+/Tm3+ co-doping reduced the recombination of photogenerated electrons and holes. • Sm3+/Tm3+ co-doping provides additional light absorption. • Sm3+/Tm3+ co-doping brings about the remarkable photocatalytic activity for CO and CH 4 production. Solar-driven photocatalytic reduction of CO 2 to fuels and chemicals with added value has attracted intense attention. Here, the Sm3+/Tm3+ co-doped BiVO 4 micro-squares were synthesized by hydrothermal method. The prepared samples were characterized by some physicochemical methods such as XRD, FT-IR, SEM, TEM, XPS, UV–Vis DRS, EPR, N 2 physisorption -desorption and electrochemical analysis. The CO 2 reduction ability of the catalysts with different rare earth content was evaluated under xenon lamp irradiation. We found that BiVO 4 photocatalyst co-doped with 10%Sm and 10%Tm (mole percent) showed the remarkable photocatalytic activity for CO and CH 4 production. The CO production rate over 10%Sm/10%Tm/BiVO 4 was around 5 times higher than that of pure BiVO 4 and single rare earth doped BiVO 4. The enhanced activity can be attributed that the Sm3+/Tm3+ co-doping reduced the recombination rate of photogenerated electrons and holes, provides additional light absorption and more active sites for CO 2 reduction. Sm3+/Tm3+ co-doping can regulate the energy band structure and carrier separation of BiVO 4 which effectively boosts the CO photocatalytic reduction for CO and CH 4 production. [Display omitted] [ABSTRACT FROM AUTHOR]

A high-performance piezoelectric photocatalyst (V-BiOIO 3 /FTCN) was constructed to improve removal efficiency of tetracycline hydrochloride (TCH). The role of V-BiOIO 3 in the composite was to introduce piezoelectric effect and construct S-scheme heterojunction photocatalyst with fish scale tubular carbon nitride (FTCN). The morphology, structure, chemical composition and optoelectronic characteristics of the as-prepared photocatalysts were studied by SEM, TEM, XRD, XPS and UV-Vis DRS. Combined with UV-Vis DRS, XPS valence band, Mott-schottky curve and theoretical calculations, the mechanism of TCH degradation was deeply analyzed. A series of degradation experiments showed that the V-BiOIO 3 /FTCN could effectively degrade TCH, and the removal efficiency was further improved under the action of ultrasound. Importantly, the further immobilized V-BiOIO 3 /FTCN/MS could float on the water surface to degrade TCH without additional stirring, which facilitated the recovery of photocatalysts and showed excellent practical application value. This work provided a reference for the design and immobilization of carbon nitride-based piezoelectric photocatalysts. [Display omitted] • Novel piezoelectric photocatalyst V-BiOIO 3 /FTCN was successfully prepared. • The transfer style of e and h+ between V-BiOIO 3 and FTCN belonged to S-scheme. • The mechanism was explored through experiments and theoretical calculations. • The floatable V-BiOIO 3 /FTCN/MS had good practical application prospects. [ABSTRACT FROM AUTHOR]

The photo-Fenton-like catalytic process has shown great application potential in environmental remediation. Herein, a novel photo-Fenton-like catalyst of Bi 2 WO 6 nanosheets decorated hortensia-like CoAl-layered double hydroxides (Bi 2 WO 6 /CoAl-LDHs) was synthesized via hydrothermal process. The optimized Bi 2 WO 6 /CoAl-LDHs composite performed the high-efficiency photo-Fenton-like catalytic performance for oxytetracycline (OTC) removal (98.47%) in the mediation of visible-light and H 2 O 2. The comparative experiment, technical characterization and density functional theory calculation results indicated that the efficient photo-Fenton-like catalytic performance of Bi 2 WO 6 /CoAl-LDHs was attributed to the synergistic action of the Fenton-like process of cobalt ions in CoAl-LDHs, an internal electric field and the S-scheme heterojunction form between Bi 2 WO 6 and CoAl-LDHs, which could significantly promote the active substance formation and the photocatalytic process in the catalytic system. This study will stimulate the new inspiration of designing the efficient catalytic system for environmental remediation and other fields. [Display omitted] • Hortensia-like Bi 2 WO 6 /CoAl-LDHs composite was synthesized via hydrothermal process. • Optical-electrical properties and H 2 O 2 adsorption behavior of samples were calculated by DFT. • Bi 2 WO 6 /CoAl-LDHs composite exhibited high photo-Fenton-like catalytic activity of antibiotic. • An internal electric field and S-scheme heterojunction form between Bi 2 WO 6 and CoAl-LDHs. [ABSTRACT FROM AUTHOR]

Due to the low efficiency of single-component nano materials, there are more and more studies on high-efficiency composites. As zero dimensional (0D) non-metallic semiconductor material, the emergence of graphene quantum dots (GQDs) overcomes the shortcomings of traditional photocatalysts (rapid rate of electron-hole recombination and narrow range of optical response). Their uniqueness is that they can combine the advantages of quantum dots (rich functional groups at edge) and sp2 carbon materials (large specific surface area). The inherent inert carbon stabilizes chemical and physical properties, and brings new breakthroughs to the development of benchmark photocatalysts. The photocatalytic efficiency of GQDs composite with semiconductor materials (SCs) can be improved by the following three points: (1) accelerating charge transfer, (2) extending light absorption range, (3) increasing active sites. The methods of preparation (bottom-up and top-down), types of heterojunctions, mechanisms of photocatalysis, and applications of GQDs/SCs (wastewater treatment, energy storage, gas sensing, UV detection, antibiosis and biomedicine) are comprehensively discussed. And it is hoped that this review can provide some guidance for the future research on of GQDs/SCs on photocatalysis. [Display omitted] • The synthesis methods of GQDs/SCs are summarized. • The roles of GQDs in improving the photocatalytic efficiency of SCs are emphasized. • Photoelectric properties and biocompatibility make GQDs/SCs are used in environment, biomedicine, etc. • The opportunities and challenges of GQDs/SCs are described. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel fish-scale tubular carbon nitride (FTCN so) was successfully prepared. • FTCN so has abundant structural defects and excellent photocatalytic performance. • The role of trithiocyanuric acid is used to build the skeleton, not for S doping. • The new 1D tubular carbon nitride composite material (Znln 2 S 4 /FTCN so) was constructed. • Znln 2 S 4 /FTCN so has excellent photocatalytic degradation tetracycline and production H 2 O 2 performance. A fish-scale tubular carbon nitride (FTCN so) and its heterojunction ZnIn 2 S 4 /FTCN so were constructed to enhance the ability of photocatalytic tetracycline degradation and H 2 O 2 production under visible light. The photocatalysts were analyzed through a variety of techniques. Firstly, the surface of FTCN so was composed of fish-scale nanoplatelets with abundant structural defects by SEM. Secondly, the results of UV–vis and theoretical calculation proved the improvement of visible light absorption performance of ZnIn 2 S 4 /FTCN so. Thirdly, the electrochemical tests confirmed the ZnIn 2 S 4 /FTCN so effectively inhibited the recombination of photogenerated e−-h+ pairs. Meanwhile, the electronic-structural properties and photocatalytic mechanism were systematically and deeply studied by combining UV–vis, XPS valence band, theoretical calculations and capture experiments of active species in different pH solution. ZnIn 2 S 4 /FTCN so exhibited excellent performance in photocatalytic tetracycline degradation and H 2 O 2 production under visible light due to the special structure and the existence of heterojunction. This work provides guidance for the development and design of new multifunctional carbon nitride-based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sulfur doped hollow tubular g-C 3 N 4 was prepared through molecular self-assembly. • A noval 2D/1D BOC/SCN hierarchical heterostructure was constructed. • BOC/SCN composites exhibited outstanding photocatalytic activity and stability for TCH degradation. • A possible Z-scheme charge transfer pathway and degradation mechanism were proposed. The construction of heterojunction photocatalysts was considered to be an effective strategy to tackle refractory pollutants. However, most of the reported composites lacked precise control of their morphology, resulting in unsatisfactory catalytic activity. In this work, we successfully fabricated sulfur doped g-C 3 N 4 hollow tubes (SCN) via molecular self-assembly, and then grew the Bi 2 O 2 CO 3 nanoflakes (BOC) in situ parallel on the surface of SCN to construct 2D/1D interfacial phase. Within 30 min visible light irradiation, the robust BOC/SCN-3 heterostructure showed considerable improvement for tetracycline degradation (82.6%) compared with individual components. This enhanced photocatalytic performance derived from the synergistic effect of S doping and heterojunction interface contact. The tubular structure formed by S doping not only narrowed the bandgap and thus boosting the visible light harvesting of CN, but also promoted electrons to travel along the 1D longitudinal and radial directions. In addition, the built-in electric field between BOC and SCN effectively achieved the spatial separation of electron-hole pairs. Mechanism analysis revealed that the h+ and •O 2 − radicals played the dominating contribution in the photocatalytic process, and a possible Z-scheme mechanism was proposed. It was expected that such design route could provide a new perspective on hierarchical heterostructure for pollutant removal. [ABSTRACT FROM AUTHOR]

• Ultrathin, porous and vacancy-rich CoAl-LDHs nanosheets were prepared by exfoliation strategy. • 2D/2D CoAl-LDHs/Ti 3 C 2 T x hybrids were synthesized via electrostatic assembly process. • Electronic and optical properties were calculated based on density functional theory. • CoAl-LDHs/Ti 3 C 2 T x hybrids exhibited high visible-light photodegradation of antibiotic. • Synergistic effect between CoAl-LDHs and Ti 3 C 2 T x endowed the excellent photocatalytic activity. The layered double hydroxides (LDHs) are potential non-noble metal photocatalysts. Unfortunately, the intrinsic activity of bulk LDHs is relatively low, which limits their use. Herein, the ultrathin, porous and vacancy-rich CoAl-LDHs nanosheets were prepared by exfoliation strategy. Then, they were assembled with the early transition-metal carbides nanosheets (MXenes, Ti 3 C 2 T x) to afford a hybrid 2D/2D CoAl-LDHs/Ti 3 C 2 T x photocatalyst via electrostatic assembly process. The experiments indicated that the CoAl-LDHs/Ti 3 C 2 T x hybrids performed an excellent visible-light photocatalytic activity for tetracycline hydrochloride (96.67 %) degradation. Diversified characterization techniques (SEM, TEM, AFM, N 2 adsorption-desorption analysis, XRD, FTIR, UV–vis DRS, photoelectrochemical test) and density functional theory calculations (electronic and optical properties) have indicated that such excellent photocatalytic activity was ascribed to the synergy and the Schottky heterojunction formation between CoAl-LDHs nanosheets and Ti 3 C 2 T x nanosheets, which possessed markedly visible-light absorption, high specific surface area, rapid electrons transfer and depressed electron-hole pairs recombination. [ABSTRACT FROM AUTHOR]

• Hollow tubular g-C 3 N 4 isotype heterojunction (SCN-CN) was synthesized. • SCN-CN performed a high visible-light photodegradation efficiency for TCH and RHB. • This work provides a theoretical basis for CN isotype heterojunction. • Electronic, optical, and work function properties were calculated based on DFT. A highly reactive hollow tubular g-C 3 N 4 isotype heterojunction (SCN-CN) was designed to enhance visible light absorption and manipulate the directed transfer of electrons and holes. The results of UV–vis DRS, XPS valence band and DFT theoretical calculations indicated S doping increases the visible-light absorption capacity and changed the ba nd gap structure of g-C 3 N 4 (CN), resulting in the transfer of electrons from the CN to the SCN and holes from the SCN to the CN under visible light. In addition, the tubular structure of the SCN-CN facilitated the transfer of electrons in the longitudinal direction, which reduced charge carrier recombination. Furthermore, the optical properties, electronic structure, and electron transfer of SCN-CN were also studied by experiments and theoretical calculations. The antibiotic tetracycline hydrochloride (TCH) and dye Rhodamine B (RHB) were subjected to evaluate the photocatalytic performance of SCN-CN. The scavenger tests and ESR data showed that the h+, ·O 2 − and ·OH worked together in the photocatalytic process. Moreover, the photocatalytic degradation pathway was analyzed by LC-MS. This study synthesized a hollow tubular CN isotype heterojunction with high visible-light photocatalytic performance and provided a theoretical basis for CN isotype heterojunction. [ABSTRACT FROM AUTHOR]