Bi2O2CO3/red phosphorus S-scheme heterojunction for H2 evolution and Cr(VI) reduction

N,S-doped Ti3C2 MXene quantum dots-anchored metal ruthenium: Efficient electrocatalyst for pH-universal hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) via water splitting is a prospective technology for achieving the sustainable production of hydrogen. So, ruthenium-based electrocatalysts have been extensively studied. However, metallic ruthenium tends to agglomerate due to the high cohesive energy, resulting in decreased HER performance in practical usage. Introducing sufficient support for dispersing and immobilizing ruthenium-based species is a viable way to enhance the utilization efficiency. MXene-based materials with unique surface termination groups, superior chemical stability, high specific surface area and favorable electrical conductivity have received significant attention as low-cost carriers for the development of active catalysts in HER. Herein, nitrogen (N) and sulfur (S) atom-doped titanium carbide (Ti3C2) quantum dots (QDs) were successfully synthesized as efficient carriers for anchoring ultra-small ruthenium nanoparticles (NPs) toward electrocatalytic HER. Electrochemical tests reveal that the resultant N,S-Ti3C2 QDs/Ru displays superior HER performance with low overpotentials of 28, 25 and 56 mV at 10 mA cm-2 current density in 0.5 M H2SO4, 1 M KOH and 1 M PBS solutions, respectively. Such a low overpotential is comparable to most previously reported non-metallic catalysts, Ru-based electrocatalysts and commercial Pt/C. In addition, N,S-Ti3C2 QDs/Ru displays extraordinarily long-term stability over a relatively wide pH range and is indeed a kind of pH-universal catalyst for hydrogen evolution. Furthermore, density functional theory (DFT) calculations demonstrate that the interactions between metal Ru and N,S-Ti3C2 MXene QDs effectively regulate the electronic structure of the active site Ru, lowering the energy barrier of the electrocatalytic HER intermediate, thus dramatically enhancing the activity for N,S-Ti3C2 QDs/Ru. This work proposes a novel approach to functionalize MXene quantum dots for use as low-cost electrocatalysts with promising practical applications in renewable energy conversion.

CuInS2/Red Phosphorus Nanosheet Interleaved Heterostructures with Improved Interfacial Charge Transfer for Photoelectrochemical Aptasensing

Accelerating the migration of interfacial carriers in heterojunctions is crucial for achieving highly sensitive photoelectrochemical (PEC) sensing. In this study, we developed three-dimensional (3D)/two-dimensional (2D) CuInS2/red phosphorus nanosheet (CuInS2/RP NS) n-n heterojunction functional materials with enhanced interfacial charge transfer capabilities for PEC sensing. The 3D CuInS2 serves as a conductive layer, providing excellent electronic conductivity and superior electron absorption and transport properties. In contrast, the ultrathin RP NS acts as a transport layer that enhances carrier mobility. The 3D/2D heterojunction ensures a large interface contact surface, shortening the carrier transport distance. A well-aligned band position generates a substantial built-in electric field, providing a significant driving force for efficient carrier separation and migration, thereby improving response sensitivity. A PEC aptamer sensor was constructed based on the synthesized heterostructure for ciprofloxacin detection. The detection limit of the CuInS2/RP NS aptamer sensor for ciprofloxacin is 2.03 × 10-15 mg·mL-1, with a linear range from 1.0 × 10-14 to 1.0 × 10-5 mg·mL-1. This work presents a strategy for enhancing the photoelectric response by modulating the interface structure of heterojunctions, thereby opening new prospects for the application of highly sensitive PEC sensors in antibiotic detection.

NiFe2O4/g-C3N4 heterostructure with an enhanced ability for photocatalytic degradation of tetracycline hydrochloride and antibacterial performance

In this work, NiFe₂O₄/g-C₃N₄ heterostructure was prepared and used for the photocatalytic decomposition of tetracycline hydrochloride antibiotic and for inactivation of E. coli bacteria. The fabricated NiFe₂O₄/g-C₃N₄ composite displayed enhanced ability for photodegradation of organic pollutants and disinfection activities compared to the bare samples, because of the enhancement of visible light absorbance, heterojunction formation and photo-Fenton process. The optimized sample 10%-NiFe₂O₄/g-C₃N₄ has photodegraded 94.5% of tetracycline hydrochloride in 80 min. The active species trapping experiments revels that ·O₂^-, h⁺ and •OH are key decomposing species participated in the antibiotic degradation. It is hoped that the present study will provide a better understanding to fabricate efficient photocatalysts for the decomposition of organic pollutants and disinfection of bacteria.