Enhanced visible-light photoelectrochemical hydrogen evolution through degradation of methyl orange in a cell based on coral-like Pt-deposited TiO2 thin film with sub-2 nm pores

Solar light driven enhanced in photocatalytic activity of novel Gd incorporated ZnO/SnO2 heterogeneous nanocomposites

The Gd-doped ZnO/SnO2 nanocomposites with various atomic percentages (0, 0.5, 0.8, and 1.2 at%) of gadolinium (coded as GdZS0, GdZS1, GdZS2, and GdZS3) was synthesis via the sol-gel method and explored for photodegradation against dye solutions exposing solar light irradiation. The synthesized nanocomposites were characterized employing the XRD, FTIR, FE-SEM, Raman spectroscopy, BET analysis and UV-Vis spectrophotometer. The FE-SEM results indicated that the formation of nanoparticles to nanoflowers covered with Gd ions was observed with an increased doping concentration of Gd. The optical bandgap was evaluated and found in the range of 3.21-3.27 eV for GdZS nanocomposites. The GdZS nano-photocatalysts were investigated against the degradation of different organic dyes and GdZS3 shows the highest degradation efficiencies of 99.3%, 98.3% and 99.4% towards MO, MB and RhB dyes, respectively at neutral pH in aqueous media. Before and after photodegradation. Biological oxygen demand and chemical oxygen demand tests to make estimations of mineralization. The investigations are very promising for the degradation process in rare earth doped metal oxide nanocomposites. A plausible photodegradation mechanism of synthesized nanocomposites under investigation has also been proposed.

AgBr nanoparticle surface modified SnO2 enhanced visible light catalytic performance: characterization, mechanism and kinetics study

In this study, a simple hydrothermal procedure and in situ precipitation method were used to prepare SnO2-AgBr composites, where the molar ratios of SnO2 and AgBr were 1 : 1, 1 : 2 and 2 : 1. Characterization results showed that the composites had excellent dispersion, crystallinity, and purity. A photocatalytic degradation experiment and first-order kinetic model indicate that SnO2-AgBr (1 : 1) had the best photocatalytic performance, and the degradation rates of 30 mg L-1 simulated MO and MG wastewater reached 96.71% and 93.36%, respectively, in 150 min, which were 3.5 times those of SnO2. The degradation rate of MO and MG increases with the dosage. Humic acid inhibited the degradation of MG, while a low concentration of humic acid promoted the degradation of MO, and the composite has good stability with pH. A free radical trapping experiment shows that ·OH and ·O2- were the main active substances, and h+ was the secondary one. According to the results of the characterization and photocatalysis experiments, a Z-scheme mechanism for the SnO2-AgBr composite was proposed, and the degradation pathway of target pollutants was speculated upon. This study has conceived novel methods for the development of a mature Z-scheme mechanism and in doing so has provided new approaches for the development of photocatalysis for water pollution control.

Recent advances and challenges of photoelectrochemical cells for hydrogen production

Photoelectrocatalytic water splitting and organic reforming have recently received significant attention among researchers due to the potential opportunity to convert sunlight into hydrogen energy using efficient and low-cost photoelectrode materials under practical operating conditions. This paper discusses an overview of various aspects related to the implementation of photoelectrochemical (PEC) cells for hydrogen generation. Information on (i) reaction energies of photosplitting and photoreforming, (ii) state-of-the-art semiconductor-based materials for PEC hydrogen evolution reaction (HER) active both under UV and visible-light irradiation, (iii) PEC photo-efficiency indicators, and (iv) criteria for the standardization of photoelectrochemical reactor performances are summarized. This short review provides a fundamental background to highlight the most effective approaches developed to date in PEC research and promote future competitive large-scale systems for hydrogen generation for practical applications.

Multifunctional cotton with PANI-Ag NPs heterojunction for solar-driven water evaporation

Water evaporation using photothermal materials is a cost-effective and sustainable technology for alleviating the world's freshwater crisis, but oil contaminants and organic pollutants exist in the original water sources, which severely degrade the evaporation performance and pose environmental hazards. In this paper, we demonstrate a photothermal material (multifunctional cotton) that simultaneously demonstrates oil-resistance, organic pollutant removal, and a high water evaporation rate. A Schottky heterostructure was formed between polyaniline (PANI) and Ag NPs, which improved the photothermal conversion and achieved a water evaporation rate of 1.37 kg m^-2 h^-1 and photothermal conversion efficiency of 84.7% under one-sun illumination (1 kW m^-2). Notably, various organic pollutants in the water source were thoroughly removed by visible-light catalytic degradation and adsorption, which displayed efficiencies of 99.3% and 97%, respectively. The multifunctional cotton also possessed excellent superoleophobicity, and repelled oil contaminants and organic pollutants in water. Considering these merits, the as-prepared multifunctional cotton is an outstanding candidate for water evaporation from various sources.

Photocatalytic kinetics of 2,4-dichloroaniline degradation by NiO-clinoptilolite nanoparticles

The ball-mill clinoptilolite nanoparticles (CNP) was ion-exchanged in Ni(II) solutions and calcined to obtain NiO-CNP catalysts with various NiO loadings. The resultant CNP was ion-exchanged in 0.1, 0.2, 0.3, and 0.4 M Ni(II) solutions and then calcined at 450 °C. The resultant NiO-CNPs contained 1.9, 2.3, 3.0, and 3.2% NiO, respectively. The XRD, FTIR, and DRS characterization techniques were applied. By applying the Scherrer equation on the XRD results, the average crystallite size for the NiO-CNP samples was estimated in the range of 42-65 nm. The pHpzc of the NiO-CNP species was slightly changed from 6.8 to 7.6 by an increase in the loaded NiO. The band gap energy of the samples was calculated by applying the Kubelka-Munk equation on the DRS results. The band gap energies of 3.81, 4.05, and 3.63 eV were estimated for the direct electronic transitions of the CN2, CN2.3, and CN3.2 samples, respectively. The boosted photoactivity was obtained in 2,4-dichloroanilyne (DCA) degradation when NiO supported onto both micronized clinoptilolite and its nanoparticles. The effects of the most important experimental variables on DCA photodegradation rate were kinetically studied by applying the Hinshelwood model on the results. The faster rate for the DCA photodegradation was achieved at the optimal conditions, including the catalyst dose: 0.5 g/L, C_DCA: 5 ppm, and the initial pH: 3. Some new peaks were observed in the HPLC chromatograms for the photodegraded DCA solutions after 180 min and 300 min, which showed 84% and 95% DCA photodegradation.

Fast Polymerization of Polydopamine Based on Titanium Dioxide for High-Performance Flexible Electrodes

Dopamine (DA) and its derivatives are promising for the fabrication of functional films and devices with excellent conductivity and long-term stability; nevertheless its polymerization process is typically prolonged. We have proposed the accelerated deposition process using ultraviolet (UV) irradiation with the existence of nanotitanium dioxide (nano-TiO₂) in order to realize the rapid and stable synthesis of polydopamine (PDA) films. The in situ deposition process of nanostructured coatings such as platinum nanowire (PtNW) was also proposed by reducing the time of polymerization process to less than 1 h. It also increased the platinum (Pt) chelating rate with PDA, which was about 12 times faster than the traditional photo-oxidation method. Compared with the electrodes of the same size based on Ti/Pt sputtering, the impedance of the proposed PDA/TiO₂/PtNW coated electrode was as low as 0.0968 ± 0.0054 kΩ at 1 kHz (reduction of 99.74%). An extremely high cathodic charge storage capacity (CSC_c) up to 234.4 ± 3.16 mC cm^-2 was also observed, which was about 106.5 and 1.6 times higher than that of Ti/Pt and PDA/PtNW electrodes, respectively. In addition to that, significant photocurrent polarization responses were presented for PDA/TiO₂/PtNW electrodes with a stable current of -136.1 μA, exhibiting excellent charge transfer and UV absorption capacities. This co-deposition method has demonstrated great potential to speed up the polymerization process and enhance the electrical performance for flexible electrodes.