Facile preparation of Zn x Cd1-x S/ZnS heterostructures with enhanced photocatalytic hydrogen evolution under visible light

Signal Modulation Induced by a Hole Transfer Layer Participant Photoactive Gate: A Highly Sensitive Organic Photoelectrochemical Transistor Sensing Platform

It is urgent to pursue appropriate gate photoactive materials for gate-to-channel signal modulation to achieve superior transconductance performances of organic photoelectrochemical transistor (OPECT) sensors. Notably, a hole transfer layer (HTL) participant CdZnS/sulfur-doped Ti3C2 MXene (S-MXene) gate was designed and developed in this work, which exhibited a remarkable signal modulation performance by up to 3 orders of magnitude. Because of the incorporation of S-MXene with an enhanced electrical conductivity as the effective HTL, the signal modulation capabilities of the CdZnS/S-MXene photoactive gate were superior to those of CdZnS and CdZnS/MXene. This incorporation inhibited the recombination of the interfacial charge and facilitated the transfer of photogenerated holes, thus enhancing the photoelectric conversion performance. This enhancement facilitated fast electron transfer with a larger effective photovoltage to augment the dedoping ability of channel ions. Based on these findings, an aptasensing platform that exhibited good performance was constructed using the proposed OPECT device, with ofloxacin as a model target and an aptamer for specific recognition. The developed OPECT aptasensor had various advantages, including a high sensitivity, good linear range (1.0 × 10-13 to 1.0 × 10-6 M), and low limit of detection (3.3 × 10-15 M). This study provided a proof-of-concept for the generalized development of HTL participant gates for OPECT sensors and other related applications.

Interfacial construction of SnS2/Zn0.2Cd0.8S nanopolyhedron heterojunctions for enhanced photocatalytic hydrogen evolution

ZnCdS, a metal chalcogenide solid solution, has attracted significant attention. However, two primary challenges hinder its widespread application in photocatalytic hydrogen evolution: the rapid recombination rate of photogenerated carriers and susceptibility to photo-oxidation in the aqueous environments. In this article, a facile hydrothermal route was employed for the first time to uniformly assemble SnS2 nanoparticles onto the surface of Zn0.2Cd0.8S (ZCS) nanopolyhedra. The intimate contact of two materials resulted in the formation of heterojunctions. By adjusting the content of SnS2, the hydrogen evolution reaction (HER) performance was optimized to reach up to 12170 μmol/gh, which is 1.9 times of the pristine ZCS. Notably, the photocatalyst demonstrated remarkable stability with an apparent quantum yield (AQY) of 15.5% at 420 nm. The enhanced photocatalytic performance can be attributed to the following factors: (i) The heterojunction composite, with larger surface area and more micropores, provides additional active sites and exhibits high photocatalytic activity; (ii) The internal electric field accelerates the separation of photogenerated carriers and reduces the recombination rate of electron-hole pairs; (iii) The photogenerated holes can be quickly transferred to the valence band of SnS2 and react with triethanolamine, thereby significantly reducing the photo-oxidation of ZCS. This work not only proposed a feasible route to improve the photocatalytic activity of ZCS, but also provided insights into the role of heterojunctions and the reaction mechanism.

Synergetic Piezo-Photocatalytic Hydrogen Evolution on Cdx Zn1-x S Solid-Solution 1D Nanorods

Conversion of solar and mechanical vibration energies for catalytic water splitting into H₂ has gained substantial attention recently. However, the sluggish charge separation and inefficient energy utilization in photocatalytic and piezocatalytic processes severely restrict the catalytic activity. In this paper, efficient piezo-photocatalytic H₂ evolution from water splitting is realized via simultaneously converting solar and vibration energy over one-dimensional (1D) nanorod-structured Cd_x Zn_1-x S (x = 0, 0.2, 0.4, 0.6, 0.8, 1) solid solutions. Under combined visible light and ultrasound irradiation, Cd_0.4 Zn_0.6 S 1D nanorods deliver a prominently synergetic piezo-photocatalytic H₂ yield rate of 4.45 mmol g^-1  h^-1 , far exceeding that under sole ultrasound or illumination. The consumedly promoted catalytic activity of Cd_0.4 Zn_0.6 S is attributed to strengthened charge separation by piezo-potential as disclosed by light-assisted scanning Kelvin probe force microscopy (SKPFM), increased strain sensitivity, and desirable optimization between piezoelectricity and visible-light response due to the formation of 1D configuration and solid solution. Metal and metal oxide depositions disclose that reduction and oxidation reactions separately occur at the tips and lateral edges of the Cd_0.4 Zn_0.6 S nanorods, in which the spatially separated reactive sites also contribute to super catalytic activity. This work is expected to inspire a new design strategy of coupled catalysis reactions for efficient renewable fuel production.