Fabrication of a Sb₂Se₃/CuSbS₂ Heterojunction Photocathode for Photoelectrochemical Water Splitting

Antimony selenide (Sb2Se3) is a promising semiconductor light-absorbing material for photoelectrochemical (PEC) water splitting to produce hydrogen. Effectively promoting the separation of photogenerated carriers and extracting holes from the light-absorbing layer to the back electrode are key to improving the PEC performance. In this work, the Sb2Se3/CuSbS2 heterojunction was prepared by a facile and cost-effective method that involves solution synthesis, spin-coating, and thermal treatment processes. The PEC performance of the Sb2Se3/CuSbS2 heterojunction was optimized by adjusting the drying temperature of the prepared CuSbS2 films. After surface passivation with TiOx, the Sb2Se3 surface defects were passivated and the PEC devices were well protected, and the Pt/TiOx/Sb2Se3/CuSbS2/FTO photocathode possessed a photocurrent density of 18.0 mA cm–2 at 0 V versus reversible hydrogen electrode, about four times that without the CuSbS2 layer. This excellent PEC performance benefits from the construction of heterojunctions with suitable energy band alignment and the improved electron–hole pair separation and transfer efficiency. This work provides an effective strategy and important guidelines for improving the PEC efficiency of the Sb2Se3 photocathode by introducing CuSbS2 to form a heterojunction

Tuning the Electrical Transport Properties of Multilayered Molybdenum Disulfide Nanosheets by Intercalating Phosphorus

We demonstrate the tuning of the electrical transport properties of MoS₂ nanosheets by intercalating phosphorus (P). The P-doped MoS₂ nanosheets were synthesized by a facile hydrothermal method. The structures and electrical properties of P-doped MoS₂ nanosheets were systematically investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, transmission electron microscopy, Raman spectral analysis, adsorption spectra analysis, and Hall measurements. The results indicate that the stacking of the (002) plane in multilayered MoS₂ nanosheets is inhibited and the interlayer spacing is enlarged with the introduction of P atoms. Both experimental results and theoretical calculations indicate that P atoms are much easier to intercalate into the interlayers of MoS₂, compared with substitution of Mo and S, which significantly affects the vibrational modes of Raman spectra. Furthermore, because of the extra electrons introduced by intercalating P atoms, the conductivity of MoS₂ could be gradually modulated from p-type to n-type by increasing the content of intercalated P. This demonstration of tuning the electrical transport properties of MoS₂ could help in the design of electrical and optoelectronic devices based on layered metal dichalcogenides

Coupling P Nanostructures with P‑Doped g‑C₃N₄ As Efficient Visible Light Photocatalysts for H₂ Evolution and RhB Degradation

Fabricating heterostructures to promote the charge separation and doping heteroatom to modulate the band gap of the photocatalysts have been regarded as effective strategies to improve the photocatalytic performance. However, it is still an unresolved issue of doping element and fabricating heterostructures with good contact at the same time. In this study, P nanostructures/P doped graphitic carbon nitride composites (P@P-<i>g</i>-C₃N₄) were successfully composited by a solid reaction route. Various structural characterizations, including X-ray adsorption near edge structure, indicate that P has been doped into g-C₃N₄ and P nanostructures were directly grown on g-C₃N₄ to form heterostructures. As expected, the intimate contacted heterostructured composites exhibit much enhanced light absorption and high-efficiency transfer and separation of photogenerated electron–hole pairs, and consequently, the composites also possess the superior photocatalytic performance in the rapidly degrading RhB and an efficient H₂ production rate of 941.80 μmolh^–1g^–1. Systematical studies combining experimental measurements with theoretical calculations were carried out to expound the underlying reasons behind the distinct performance. This study pave a one-step way to synthesize earth abundant element C, N, and P as novel photocatalysts for photochemical applications

Assembly of One-Dimensional Organic Luminescent Nanowires Based on Quinacridone Derivatives

The quinacridone derivatives N,N‘-dialkyl-1,3,8,10-tetramethylquinacridone (CnTMQA, n = 6, 10, 14) were used as building blocks to assemble luminescent nano- and microscale wires. It was demonstrated that CnTMQA with different lengths of alkyl chains display obviously different wire formation properties. C10TMQA and C14TMQA showed a stronger tendency to form 1-D nano- and microstructures compared with C6TMQA. The C10TMQA molecules could be employed to fabricate the wires with different diameters, which exhibited a size-dependent luminescence property. The emission spectrum of the C10TMQA wires with diameters of 200−500 nm shows a broad emission band at 560 nm and a shoulder at around 535 nm, while the emission spectrum of the C10TMQA wires with diameters of 2−3 μm reveals a narrower emission band at 563 nm. For the CnTMQA-based samples with different morphologies, the emission property change tendency agrees with that of the powder X-ray diffraction patterns of these samples

Architecting the metal-nonmetal oxide layers for boosting the oxygen-evolving intrinsic activity of amorphous alloy

Designing high-efficiency and freestanding electrocatalysts hold immense importance in addressing the limitations of powdered electrocatalysts and accelerating the sluggish kinetics of the oxygen evolution reaction (OER) in advancing energy technologies. While dealloyed amorphous ribbons have been shown to be active and self-supporting electrocatalysts toward OER, the underlying enhancement mechanism remains unclear. Here, we developed a dealloyed Ni-Fe-B-Si-P amorphous electrocatalysts with a mixed oxide layer (including oxo-anions: phosphate, silicate, and borate). The dealloyed oxide layer optimizes the surface properties and chemical local environment of the amorphous ribbon, then shortens the multistep evolution path (Ni0 → Ni2+ → Ni3+ → Ni4+) toward Ni4+ species during the surface reconstruction process and decreased energy barriers for the dealloyed Ni-Fe-B-Si-P electrocatalyst during OER. Benefiting from the changes, the dealloyed Ni-Fe-B-Si-P enables a 56-fold increase in current density (at overpotential: 320 mV) and an 8-fold increase in turnover frequency values compared to undealloyed Ni-Fe-B-Si-P, demonstrating the major effect of the intrinsic activity on the OER performance of the dealloyed ribbon. This work sheds light on the enhancement mechanism of amorphous bulk electrocatalysts and offers valuable insights into the rational design of amorphous components and surface treatment processes

Low Threshold and Ultrastability of One-Step Air-Processed All-Inorganic CsPbX₃ Thin Films toward Full-Color Visible Amplified Spontaneous Emission

All-inorganic perovskites (CsPbX3) with the merits of high stability and remarkable optical gain property are attractive for achieving on-chip coherent light sources. Unfortunately, traditional solution-processed CsPbX3 films suffer from inevitable poor surface integrity and pinhole defects, severely hindering their optical properties. Here, from the perspective of precursor solution chemistry, we use an ionic liquid solvent methylammonium acetate (MAAc) to fabricate compact, pinhole-free, and smooth CsPbX3 thin films in a one-step air process without antisolvent treatment. Optically pumped amplified spontaneous emission (ASE) with a straightforward visible spectral tunability (418–725 nm) is achieved under both nanosecond and femtosecond laser excitation. For the representative CsPbBr3 films, the threshold reaches down to 11.4 μJ cm–2 under nanosecond laser pumping, which is comparable to the value under one-photon femtosecond pumping. The long gain lifetime up to 258.2 ps is revealed by transient absorption spectroscopy. Most importantly, the films show excellent optical stability and humidity stability with no obvious degradation under the pulsed laser irradiation for more than 210 min, stable ASE output under 95% high humidity, and conspicuous ASE after 1000 h of storage in air condition without encapsulation. These results demonstrate that the method of fabricating inorganic perovskite films with an ionic liquid solvent is promising in developing high-performance full-color visible lasers