Sodium Hexa-Titanate Nanowires Modified with Cobalt Hydroxide Quantum Dots as an Efficient and Cost-Effective Electrocatalyst for Hydrogen Evolution in Alkaline Media

A novel electrocatalyst with high activity and enhanced durability toward the hydrogen evolution reaction (HER) in alkaline media has been designed and fabricated based on sodium hexa-titanate (Na₂Ti₆O₁₃) nanowires synthesized by a hydrothermal process and modified with Co(OH)₂ quantum dots (QDs) by a facile chemical bath deposition (CBD) method. The current response of the developed Ti/Na₂Ti₆O₁₃/Co(OH)₂ nanocomposite electrode attained 10 mA cm^-2 at an overpotential of 159 mV. The nanocomposite electrode exhibited a high stability at an applied current of 100 mA cm^-2. The remarkable catalytic behavior was achieved with a loading amount of ca. 0.06 mg cm^-2 cobalt hydroxide. This is attributed to the high electrochemically active surface area (EASA) gained by the nanowire-structured substrate and considerable enhancement of electrochemical conductivity with the use of Co(OH)₂ quantum dots as an active material. The superior catalytic activity and high stability show that the developed catalyst is a promising candidate for hydrogen production in alkaline media.

Facile Formation of Anatase Nanoparticles on H-Titanate Nanotubes at Low Temperature for Efficient Visible Light-Driven Degradation of Organic Pollutants

Anatase nanoparticles (5–10 nm) generated on H-titanate nanotube surface (H-titanate/anatase) were prepared by an ingenious and simple method. H-titanate tubes were prepared by a hydrothermal reaction of Ti powder in concentrated NaOH solution and an ion exchange process with HNO3 solution. After that, at a relatively low drying temperature (100 °C), a small quantity of anatase nanoparticles were in-situ formed on the H-titanate tubes surface by a surface dehydration reaction. In-situ transformation can form a strong interface coupling between H-titanate and anatase, which is conducive to accelerating charge transfer and improving its photocatalytic activity. In addition, the smaller average crystal size, the large specific surface areas (BET), the nanotubed and layered structure and the synergistic effect of dual phases would be beneficial to improving the photocatalytic efficiency.

Core-Shell Heterostructured and Visible-Light-Driven Titanoniobate/TiO2 Composite for Boosting Photodegradation Performance

Herein, we report a one-dimensional (1D) S-doped K3Ti5NbO14@TiO2 (STNT) core-shell heterostructured composite with an enhanced photocatalytic degradation activity under visible light, which was prepared by a simple reassembly-calcination method using thiourea as the S source. The anisotropically shaped rods are favorable for the rapid transport of photogenerated charge carriers. The substitution of Ti4+ by S6+ is primarily incorporated into the lattice of the TiO2 shell so as to create an intra-band-gap state below the conduction band (CB) position, giving rise to Ti-O-S bonds and thus the visible light response. The presence of electron-deficient S atoms is of benefit to the decreased recombination rate of photogenerated electrons and holes by capturing electrons (e-). Meanwhile, a tight close interface between K3Ti5NbO14 and TiO2 was formed to achieve a nano-heterojunction structure, leading to the fostered separation of its interfacial photogenerated electrons and holes. The visible-light-driven photocatalytic degradation of methylene blue (MB) by STNT composites is higher than that by pure K3Ti5NbO14, owing to the synergistic effects of S doping and heterojunction. A possible photocatalytic mechanism was proposed with a reasonable discussion. This work may provide an insight into constructing highly efficient core-shell photocatalysts used toward sustainable environmental remediation and resource shortages.

N-Doped K3Ti5NbO14@TiO2 Core-Shell Structure for Enhanced Visible-Light-Driven Photocatalytic Activity in Environmental Remediation

A novel N-doped K3Ti5NbO14@TiO2 (NTNT) core-shell heterojunction photocatalyst was synthesized by firstly mixing titanium isopropoxide and K3Ti5NbO14 nanobelt, and then calcinating at 500 °C in air using urea as the nitrogen source. The samples were analyzed by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis absorption spectroscopy and X-ray photoelectron spectroscopic (XPS) spectra. Anatase TiO2 nanoparticles were closely deposited on the surface of K3Ti5NbO14 nanobelt to form a nanoscale heterojunction structure favorable for the separation of photogenerated charge carriers. Meanwhile, the nitrogen atoms were mainly doped in the crystal lattices of TiO2, resulting in the increased light harvesting ability to visible light region. The photocatalytic performance was evaluated by the degradation of methylene blue (MB) under visible light irradiation. The enhanced photocatalytic activity of NTNT was ascribed to the combined effects of morphology engineering, N doping and the formation of heterojunction. A possible photocatalytic mechanism was proposed based on the experimental results.

Lead-free organic–inorganic hybrid perovskite heterojunction composites for photocatalytic applications

Heterojunction structured MASnI₃/TiO₂ photocatalysts (MA represents CH₃NH₃⁺) are prepared via a facile wet-chemical method and characterized by various techniques.

Ultrathin anatase nanosheets with high energy facets exposed and related photocatalytic performances

Ultrathin anatase nanosheets with high energy (116) facets exposed were fabricated from exfoliated titanate nanosheets and exhibited high photocatalytic performance.

S-doped mesoporous nanocomposite of HTiNbO5 nanosheets and TiO2 nanoparticles with enhanced visible light photocatalytic activity

S-doped mesoporous TiO₂/HTiNbO₅ nanocomposite showed dramatically enhanced visible-light photocatalytic activity and stability owing to the combined effects of nano-heterojunction, S doping and morphology engineering.