Enhanced Light Absorption and Photo-Generated Charge Separation Efficiency for Boosting Photocatalytic H2 Evolution through TiO2 Quantum Dots with N-Doping and Concomitant Oxygen Vacancy.

Low-range light absorption and rapid recombination of photo-generated charge carriers have prevented the occurrence of effective and applicable photocatalysis for decades. Quantum dots (QDs) offer a solution due to their size-controlled photon properties and charge separation capabilities. Herein, well-dispersed interstitial nitrogen-doped TiO2 QDs with stable oxygen vacancies (N-TiO2-x-VO) are fabricated by using a low-temperature, annealing-assisted hydrothermal method. Remarkably, electrostatic repulsion prevented aggregation arising from negative charges accumulated in situ on the surface of N-TiO2-x-VO, enabling complete solar spectrum utilization (200-800 nm) with a 2.5 eV bandgap. Enhanced UV-vis photocatalytic H2 evolution rate (HER) reached 2757 µmol g-1 h-1, 41.6 times higher than commercial TiO2 (66 µmol g-1 h-1). Strikingly, under visible light, HER rate was 189 µmol g-1 h-1. Experimental and simulated studies of mechanisms reveal that VO can serve as an electron reservoir of photo-generated charge carriers on N-doped active sites, and consequently, enhance the separation rate of exciton pairs. Moreover, the negative free energy (-0.35 V) indicates more favorable thermodynamics for HER as compared with bulk TiO2 (0.66 V). This research work paves a new way of developing efficient photocatalytic strategies of HER that are applicable in the sustainable carbon-zero energy supply.

High-efficiency photoreduction of CO2 in a low vacuum.

Photoreduction of CO2 into CO, CH4 or hydrocarbons is attractive, due to environmental compatibility and economic feasibility. Optimizing the reaction engineering of CO2 reduction is an effective and general strategy that should be given special consideration. In this article, the photocatalytic CO2 reduction performances are originally investigated in a low vacuum in both dilute (10%) and pure CO2. We discover that the CH4 yield increased above one hundred times as the vacuum degree increased from barometric pressure to -80 kPa in dilute CO2. It also reveals long-term stability and good cycling performance in a low vacuum. The enhanced CO2 photoreduction performance in a low vacuum comes from better accumulation of photogenerated electrons, less intense Brownian movement of gas molecules in the environment and hindrance of the active site-blocking of gas molecules in the environment. Improved photocatalytic CO2 reduction in a low vacuum is further verified by Pt-TiO2 catalysts. This research presents a general route for producing clean fuels by photocatalytic CO2 reduction in a more effective way.

Hydrophobic Surface Array Structure Based on Laser-Induced Graphene for Deicing and Anti-Icing Applications.

The exceptional performance of graphene has driven the advancement of its preparation techniques and applications. Laser-induced graphene (LIG), as a novel graphene preparation technique, has been applied in various fields. Graphene periodic structures created by the LIG technique exhibit superhydrophobic characteristics and can be used for deicing and anti-icing applications, which are significantly influenced by the laser parameters. The laser surface treatment process was simulated by a finite element software analysis (COMSOL Multiphysics) to optimize the scanning parameter range, and the linear array surface structure was subsequently fabricated by the LIG technique. The generation of graphene was confirmed by Raman spectroscopy and energy-dispersive X-ray spectroscopy. The periodic linear array structure was observed by scanning electron microscopy (SEM) and confocal laser imaging (CLSM). In addition, CLSM testings, contact angle measurements, and delayed icing experiments were systematically performed to investigate the effect of scanning speed on surface hydrophobicity. The results show that high-quality and uniform graphene can be achieved using the laser scanning speed of 125 mm/s. The periodic linear array structures can obviously increase the contact angle and suppress delayed icing. Furthermore, these structures have the enhanced ability of the electric heating deicing, which can reach 100 °C and 240 °C within 15 s and within 60 s under the DC voltage power supply ranging from 3 to 7 V, respectively. These results indicate that the LIG technique can be developed to provide an efficient, economical, and convenient approach for preparing graphene and that the hydrophobic surface array structure based on LIG has considerable potential for deicing and anti-icing applications.

Fusion Bonding Possibility for Incompatible Polymers by the Novel Ultrasonic Welding Technology: Effect of Interfacial Compatibilization.

Fusion bonding for polymers has been successfully welded for the same and dissimilar materials. However, it is difficult to bond incompatible polymers due to poor interfacial adhesion. Usually, interfacial compatibilization can resolve this problem. According to the mechanism, an interlayer solder sheet (ISS) consisting of maleic anhydride-functionalized polypropylene (PP-g-MAH) and polyamide6 (PA6) was introduced into the ultrasonic welding (USW) device. In this way, it successfully realized the weldability between PP and PA6. The welding strength of PP-PA6 reached 22.3 MPa, about 84% welding strength for the PP body and 63% tensile strength for PP. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) showed the formation of PP-g-PA6 copolymer in blends. This copolymer played the role of an emulsifier, which enhanced the interfacial adhesion between PP and PA6 in two phases, leading to micron-scale homogeneity. In the USW process, the copolymer could act as a bridge between PP and PA6 molecular chains to realize the fusion bonding of incompatible polymers. Finally, we proposed the fusion bonding model for PP-PA6 interfaces.

Bi-Metal Phosphide NiCoP: An Enhanced Catalyst for the Reduction of 4-Nitrophenol.

Porous phosphide NixCoyP composite nanomaterials are successfully synthesized at different Ni/Co ratios (=0, 0.5, 1, and 2) to reduce 4-nitrophenol. The X-ray diffraction and X-ray photoelectron spectroscopy results demonstrate that the products are CoP, NiCoP/CoP, NiCoP, and NiCoP/Ni2P when the Ni/Co ratio is 0, 0.5, 1, and 2, respectively. The products exhibit different catalytic performance for reduction of 4-nitrophenol at room temperature. Among them, the pure NiCoP delivers a better catalytic efficiency with k app = 677.4 × 10 - 2   min - 1 and k = 338.7   ( Lg - 1 min - 1 ) , due to the synergy between Ni and Co atoms. The sequence of catalytic efficiency of different samples is CoP < NiCoP/CoP < NiCoP/Ni2P < NiCoP.

PEDOT coated iron phosphide nanorod arrays as high-performance supercapacitor negative electrodes.

PEDOT coated iron phosphide nanorod arrays are synthesized and demonstrated as high-performance negative electrodes for supercapacitors with high areal specific capacitance and significantly improved cycling stability. A MnO2//FeP/PEDOT aqueous asymmetric supercapacitor is fabricated with a high volumetric capacitance of 4.53 F cm-3 and an energy density of 1.61 mW h cm-3.

Influence of different aluminum salts on the photocatalytic properties of Al doped TiO2 nanoparticles towards the degradation of AO7 dye.

Three kinds of Al-TiO2 samples and pure TiO2 samples were synthesized via a modified polyacrylamide gel route using different aluminum salts, including Al2(SO4)3∙18H2O, AlCl3, and Al(NO3)3∙9H2O under identical conditions. The influence of different aluminum salts on the phase purity, morphologies, thermal stability of anatase and photocatalytic properties of the as-prepared Al-TiO2 nanoparticles were studied. The energy gap (Eg) of Al-TiO2 nanoparticles decreases due to Al ion doping into TiO2. The photocatalytic activities of the Al-TiO2 samples were investigated by the degradation of acid orange 7 dye in aqueous solution under simulated solar irradiation. The Al-TiO2 nanoparticles prepared from Al(NO3)3∙9H2O exhibit the best photocatalytic activity among the four kinds of samples, followed in turn by the Al-TiO2 nanoparticles prepared with AlCl3, Al2(SO4)3∙18H2O and pure TiO2. The different performances are attributed to complex effects of Eg, particle size, surface morphology, phase purity and the defect sites of the Al-TiO2 nanoparticles.