Construction of a g-C3N4/Bi(OH)3 Heterojunction for the Enhancement of Visible Light Photocatalytic Antibacterial Activity.

Photocatalytic technology has been recently conducted to remove microbial contamination due to its unique features of nontoxic by-products, low cost, negligible microbial resistance and broad-spectrum elimination capacity. Herein, a novel two dimensional (2D) g-C3N4/Bi(OH)3 (CNB) heterojunction was fabricated byincorporating Bi(OH)3 (BOH) nanoparticles with g-C3N4 (CN) nanosheets. This CNB heterojunction exhibited high photocatalytic antibacterial efficiency (99.3%) against Escherichia coli (E. coli) under visible light irradiation, which was 4.3 and 3.4 times that of BOH (23.0%) and CN (28.0%), respectively. The increase in specific surface area, ultra-thin layered structure, construction of a heterojunction and enhancement of visible light absorption were conducive to facilitating the separation and transfer of photoinduced charge carriers. Live/dead cell staining, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) assays and scanning electron microscopy (SEM) have been implemented to investigate the damage to the cell membrane and the leakage of the intracellular protein in the photocatalytic antibacterial process. The e-, h+ and O2•- were the active species involved in this process. This study proposed an appropriate photocatalyst for efficient treatment of bacterial contamination.

The Synergistic Effect of Adsorption-Photocatalysis for Removal of Organic Pollutants on Mesoporous Cu2V2O7/Cu3V2O8/g-C3N4 Heterojunction.

Cu2V2O7/Cu3V2O8/g-C3N4 heterojunctions (CVCs) were prepared successfully by the reheating synthesis method. The thermal etching process increased the specific surface area. The formation of heterojunctions enhanced the visible light absorption and improved the separation efficiency of photoinduced charge carriers. Therefore, CVCs exhibited superior adsorption capacity and photocatalytic performance in comparison with pristine g-C3N4 (CN). CVC-2 (containing 2 wt% of Cu2V2O7/Cu3V2O8) possessed the best synergistic removal efficiency for removal of dyes and antibiotics, in which 96.2% of methylene blue (MB), 97.3% of rhodamine B (RhB), 83.0% of ciprofloxacin (CIP), 86.0% of tetracycline (TC) and 80.5% of oxytetracycline (OTC) were eliminated by the adsorption and photocatalysis synergistic effect under visible light irradiation. The pseudo first order rate constants of MB and RhB photocatalytic degradation on CVC-2 were 3 times and 10 times that of pristine CN. For photocatalytic degradation of CIP, TC and OTC, it was 3.6, 1.8 and 6.1 times that of CN. DRS, XPS VB and ESR results suggested that CVCs had the characteristics of a Z-scheme photocatalytic system. This study provides a reliable reference for the treatment of real wastewater by the adsorption and photocatalysis synergistic process.

Effective Removal of Methylene Blue on EuVO4/g-C3N4 Mesoporous Nanosheets via Coupling Adsorption and Photocatalysis.

In this study, we first manufactured ultrathin g-C3N4 (CN) nanosheets by thermal etching and ultrasonic techniques. Then, EuVO4 (EV) nanoparticles were loaded onto CN nanosheets to form EuVO4/g-C3N4 heterojunctions (EVCs). The ultrathin and porous structure of the EVCs increased the specific surface area and reaction active sites. The formation of the heterostructure extended visible light absorption and accelerated the separation of charge carriers. These two factors were advantageous to promote the synergistic effect of adsorption and photocatalysis, and ultimately enhanced the adsorption capability and photocatalytic removal efficiency of methylene blue (MB). EVC-2 (2 wt% of EV) exhibited the highest adsorption and photocatalytic performance. Almost 100% of MB was eliminated via the adsorption-photocatalysis synergistic process over EVC-2. The MB adsorption capability of EVC-2 was 6.2 times that of CN, and the zero-orderreaction rate constant was 5 times that of CN. The MB adsorption on EVC-2 followed the pseudo second-order kinetics model and the adsorption isotherm data complied with the Langmuir isotherm model. The photocatalytic degradation data of MB on EVC-2 obeyed the zero-order kinetics equation in 0-10 min and abided by the first-order kinetics equation for10-30 min. This study provided a promising EVC heterojunctions with superior synergetic effect of adsorption and photocatalysis for the potential application in wastewater treatment.

Oligomer-Assisted Photoactive Layers Enable >18 % Efficiency of Organic Solar Cells.

Although ternary organic solar cells (OSCs) have unique advantages in improving device performance, the morphology assembly in the ternary-phase would be more uncertain or complex than that in the binary-phase. Here, we propose a new concept of oligomer-assisted photoactive layers for high-performance OSCs. The formed alloy-like phase of the oligomer : host polymer blend enabled the oligomer-assisted OSCs to fuse the advantages of both binary and ternary devices, exhibiting substantially enhanced performance and stability compared to the control devices. With the addition of oligomers, outstanding efficiencies of 17.33 % for a PM6 : Y6 device, 18.32 % for a PM6 : BTP-eC9 device, and 17.13 % for a PM6/Y6 pseudo-bilayer device were achieved, all of which are one of the highest values in their corresponding fields. The improved performance originated from the downshift energy levels, enhanced light absorption, optimized blend morphology, favorable charge dynamics, and reduced non-radiative energy loss.

Random Copolymerization Strategy for Host Polymer Donor PM6 Enables Improved Efficiency Both in Binary and Ternary Organic Solar Cells.

Although breakthroughs have been made in organic solar cells (OSCs) in recent years, the power conversion efficiency (PCE) of OSCs still lags behind inorganic/perovskite solar cells. In this work, two terpolymers were synthesized by introducing the thieno[3,4-c]pyrrole-4,6-(5H)-dione (TPD) block into the host polymer donor PM6. Owing to the lower highest occupied molecular orbital energy level, wider light absorption, optimal molecular packing, and more desirable aggregation morphology by addition of the TPD, the PM6-TPD-5 % : Y6-based device displayed an improved PCE of 16.3 % with an enhanced open-circuit voltage (VOC ) of 0.860 V, relative to that of PM6-TPD-10 % : Y6 (PCE=14.8 %) and PM6 : Y6-based device (PCE=15.6 %). Interestingly, the VOC did not always increase in proportion to the third component. Besides, ternary OSCs based on PM6 : PM6-TPD-5 % : Y6 achieved a superior PCE of 17.1 %. This work demonstrated that random copolymerization is a feasible and effective strategy to further increase device performance, and the two polymers that possess similar structure and absorption in ternary devices can also obtain impressive efficiency.

Recent Developments of n-Type Organic Thermoelectric Materials: Influence of Structure Modification on Molecule Arrangement and Solution Processing.

Organic semiconductor (OSCs) thermoelectric materials have been studied widely due to their low thermal conductivity and solution processing characteristics. Currently, the high conductivity (up to 1000 s cm-1 ) has boosted the performance of p-type organic thermoelectric materials substantially. In contrast, the development of n-type organic thermoelectric materials is still limited by their low mobility, inferior air stability, and poor doping efficiency, which is relevant to the molecule structure and dopant dispersion. Herein, the recent development of n-type organic thermoelectric materials was reviewed with an emphasis on molecule structure modification and solution processing. Methods for optimizing conjugate structure were summarized from the effects of conjugated backbone modification and side chains diversification on molecular stacking. The primary n-type dopants were also summarized briefly. Especially, the role of solution aggregation controlling on film preparation and properties was given special attention. Additionally, the emergence of organic diradicals with low lowest unoccupied molecular orbital energy level and no doping was introduced, which shows great potential in n-type organic thermoelectric materials. All these endeavors have led to the development of n-type OSCs materials. This Review is aimed at illustrating the state-of-the-art progress and providing some guideline for the design of organic thermoelectric materials in the future.

Exploiting Novel Unfused-Ring Acceptor for Efficient Organic Solar Cells with Record Open-Circuit Voltage and Fill Factor.

Unfused-ring acceptors (UFAs) show bright application prospects in organic solar cells (OSCs) thanks to their easy synthesis, low cost, and good device performance. The selection of central-core building block and suitable side chain are the key factors to achieve high-performance UFAs. Current tremendous endeavors for the development of UFAs mainly concentrate on obtaining higher short-circuit current density (Jsc ), albeit accompanied by low open-circuit voltage (Voc ) and modest fill factor (FF). Herein, two novel A-D-A'-D-A type UFAs (BTCD-IC and BTCD-2FIC), which have the same new electron-withdrawing central-core dithieno[3',2':3,4;2'',3'':5,6]-benzo[1,2-c][1,2,5]thiadia-zole (DTBT) and cyclopentadithiophene unit (CPDT, substituted by 2-butyl-1-octyl alkyl chain) coupling with different terminals, were designed and synthesized. Two UFAs showed strong and broad light absorption in the wavelength range of 300-850 nm owing to the strong intramolecular charge transfer effect favorable by DTBT core. Compared with BTCD-IC, BTCD-2FIC with F-containing terminal group exhibited higher molar extinction coefficient, lower energy level, higher charge mobility, stronger crystallinity, more ordered molecular stacking, and better film morphology. As a result, when blended with donor polymer PBDB-T (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c']-dithiophene-4,8-dione)]), the BTCD-2FIC-based OSC achieved a superior power conversion efficiency (PCE) of 11.32 %, with a high Voc of 0.85 V, a Jsc of 18.24 mA cm-2 , and a FF of 73 %, than BTCD-IC-based OSC (PCE=8.96 %). Impressively, the simultaneously enhanced Voc and FF values of the PBDB-T:BTCD-2FIC device were the highest values of the A-D-A'-D-A-type UFAs. The results demonstrate the application of electron-withdrawing DTBT central-core unit in efficient UFAs provides meaningful molecular design guidance for high-performance OSCs.