One-pot hydrothermal preparation of wurtzite CuGaS2 and its application as a photoluminescent probe for trace detection of l-noradrenaline

Wurtzite CuGaS2 with an In-Situ-Formed CuO Layer Photocatalyzes CO2 Conversion to Ethylene with High Selectivity

We present surface reconstruction-induced C-C coupling whereby CO₂ is converted into ethylene. The wurtzite phase of CuGaS_2. undergoes in situ surface reconstruction, leading to the formation of a thin CuO layer over the pristine catalyst, which facilitates selective conversion of CO₂ to ethylene (C₂ H₄ ). Upon illumination, the catalyst efficiently converts CO₂ to C₂ H₄ with 75.1 % selectivity (92.7 % selectivity in terms of R_electron ) and a 20.6 μmol g^-1  h^-1 evolution rate. Subsequent spectroscopic and microscopic studies supported by theoretical analysis revealed operando-generated Cu²⁺ , with the assistance of existing Cu⁺ , functioning as an anchor for the generated *CO and thereby facilitating C-C coupling. This study demonstrates strain-induced in situ surface reconstruction leading to heterojunction formation, which finetunes the oxidation state of Cu and modulates the CO₂ reduction reaction pathway to selective formation of ethylene.

Sensitive detection of noradrenaline in human whole blood based on Au nanoparticles embedded vertically-ordered silica nanochannels modified pre-activated glassy carbon electrodes

Sensitive determination of noradrenaline (NE), the pain-related neurotransmitters and hormone, in complex whole blood is of great significance. In this work, an electrochemical sensor was simply constructed on the pre-activated glassy carbon electrode (p-GCE) modified with vertically-ordered silica nanochannels thin film bearing amine groups (NH₂-VMSF) and in-situ deposited Au nanoparticles (AuNPs). The simple and green electrochemical polarization was employed to pre-activate GCE to realize the stable binding of NH₂-VMSF on the surface of electrode without the use of any adhesive layer. NH₂-VMSF was conveniently and rapidly grown on p-GCE by electrochemically assisted self-assembly (EASA). With amine group as the anchor sites, AuNPs were in-situ electrochemically deposited on the nanochannels to improve the electrochemical signals of NE. Owing to signal amplification from gold nanoparticles, the fabricated AuNPs@NH₂-VMSF/p-GCE sensor can achieve electrochemical detection of NE ranged from 50 nM to 2 μM and from 2 μM to 50 μM with a low limit of detection (LOD) of 10 nM. The constructed sensor exhibited high selectivity and can be easily regenerated and reused. Owing to the anti-fouling ability of nanochannel array, direct electroanalysis of NE in human whole blood was also realized.

Snowflake-like Metastable Wurtzite CuGaS2/MoS2 Composite with Superior Electrochemical HER Activity

In the present work, we report the synthesis of wurtzite CuGaS₂ and its composite with MoS₂ and explored their efficacy toward two important applications, viz. electrocatalytic hydrogen evolution reaction (HER) and adsorption of Rhodamine B dye. The CuGaS₂ was synthesized via a low-temperature ethylenediamine-mediated solvothermal method. The obtained products were characterized by various techniques such as X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy to ascertain the phase formation, surface morphology, and elemental oxidation states. The electrocatalytic activity of the wurtzite CuGaS₂ and CuGaS₂/MoS₂ composites toward HER was investigated, wherein the CuGaS₂/MoS₂ composite exhibited superior activity when compared to the pristine sample with a small Tafel slope of 56.2 mV dec^-1 and an overpotential value of -464 mV at the current density of 10 mA cm^-2. On the other hand, the synthesized CuGaS₂ also showed an impressive adsorption behavior toward Rhodamine B dye with 99% adsorption in 60 min, which is relatively better than that observed with the composite material.

Stabilizing CuGaS2 by crystalline CdS through an interfacial Z-scheme charge transfer for enhanced photocatalytic CO2 reduction under visible light

CuGaS2 is one of the most excellent visible-light-active photocatalysts for CO2 reduction and water splitting. However, CuGaS2 suffers from serious deactivation in photocatalytic reactions, which is mainly due to the photo-oxidation induced self-corrosion (Cu+ to Cu2+). Here, we constructed a CuGaS2/CdS hybrid photocatalyst dominated by a Z-scheme charge transfer mechanism. The transfer of photo-generated electrons from excited nanocrystalline CdS to CuGaS2 across the coherent interface reduces Cu2+ formation and favors Cu+ regeneration. This process suppresses the deactivation of CuGaS2 and maintains high performance. Both the activity and stability of photocatalytic CO2 reduction to produce CO over the CuGaS2/CdS hybrid were remarkably improved, which was approximately 4-fold higher than CuGaS2 and 3-fold higher than CdS in converting CO2 into CO. Our study demonstrates that even using the semiconductors prone to photo-corrosion, it is possible to obtain satisfactory catalytic activity and stability by designing efficient Z-scheme-charge-transfer-type photocatalysts.

Compound Copper Chalcogenide Nanocrystals

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), energy storage (lithium-ion batteries, hydrogen generation), emissive materials (plasmonics, LEDs, biolabelling), sensors (electrochemical, biochemical), biomedical devices (magnetic resonance imaging, X-ray computer tomography), and medical therapies (photochemothermal therapies, immunotherapy, radiotherapy, and drug delivery). The confluence of advances in the synthesis, assembly, and application of these NCs in the past decade has the potential to significantly impact society, both economically and environmentally.

Recent progress in quantum dot based sensors

Recent progress in quantum dot (QD) based chemo- and biosensors for various applications is summarized.