Tunable 0D/2D/2D Nanocomposite Based on Green Zn-Doped CuInS2 Quantum Dots and MoS2/rGO as Photoelectrodes for Solar Hydrogen Production

Recent advances in photoelectrochemical hydrogen production using I-III-VI quantum dots

Photoelectrochemical (PEC) water splitting, recognized for its potential in producing solar hydrogen through clean and sustainable methods, has gained considerable interest, particularly with the utilization of semiconductor nanocrystal quantum dots (QDs). This minireview focuses on recent advances in PEC hydrogen production using I-III-VI semiconductor QDs. The outstanding optical and electrical properties of I-III-VI QDs, which can be readily tuned by modifying their size, composition, and shape, along with an inherent non-toxic nature, make them highly promising for PEC applications. The performance of PEC devices using these QDs can be enhanced by various strategies, including ligand modification, defect engineering, doping, alloying, and core/shell heterostructure engineering. These approaches have notably improved the photocurrent densities for hydrogen production, achieving levels comparable to those of conventional heavy-metal-based counterparts. Finally, this review concludes by addressing the present challenges and future prospects of these QDs, underlining crucial steps for their practical applications in solar hydrogen production.

Self-powered photoelectrochemical immunosensing platform for sensitive CEA detection using dual-photoelectrode synergistic signal amplification

Self-powered photoelectrochemical (PEC) sensing, as an emerging sensing mode, can effectively solve the problems such as weak anti-interference ability and poor signal response of individual photoanode or photocathode sensing. In this work, an ITO/Co-CuInS2 photocathode and ITO/WO3@CdS photoanode based self-powered cathodic PEC immunosensor was developed, which integrated dual-photoelectrode to synergistic amplify the signal for highly sensitive and specific detection of carcinoembryonic antigen (CEA). The self-powered PEC sensor could drive electrons transfer through the difference in Fermi levels between the two photoelectrodes without an external bias voltage. The photoanode was introduced to amplify the photoelectric signal, and the photocathode was only designed for the construction of sensing interfaces. The proposed sensor quantitatively determined the target CEA with the detection limit of 0.23 pg/mL and a linear correlation confine of 0.1 pg/mL ∼100 ng/mL. The constructed immunosensing platform exhibited high sensitivity, satisfactory stability and great biological detection selectivity, providing a feasible and effective strategy for the manufacture of new self-powered sensors in high-performance PEC bioanalytical applications.

Versatile photoelectrochemical biosensor based on AIS/ZnS QDs sensitized-WSe2 nanoflowers coupled with DNA nanostructure probe for"On-Off"assays of TNF-α and MTase

Herein, a novel multifunctional photoelectrochemical (PEC) biosensor based on AgInS2 (AIS)/ZnS quantum dots (QDs) sensitized-WSe2 nanoflowers and DNA nanostructure signal probe was designed to achieve ultra-sensitive "On-Off" detection of human tumor necrosis factor α (TNF-α) and methylase Dam MTase (MTase). AIS/ZnS QDs as an excellent photosensitive material was found to match WSe2 in energy level for the first time, and the photocurrent signal after sensitization was 65 times that of WSe2 nanoflowers and 17.9 times that of AIS/ZnS QDs. Moreover, abundant AIS/ZnS QDs were loaded on the TiO2 nanoparticles with good conductivity by DNA to fabricate a multifunctional probe, which can not only amplify signal but also specifically recognize target. When target TNF-α was present, the AIS/ZnS QDs signal probe was attached to the WSe2 nanoflowers-modified electrode through binding to aptamer, and the amplified PEC signal was generated for "on" assay of TNF-α. Furthermore, Dam MTase as second target induced methylation of hairpin HDam, so it is cleaved by the endonuclease DpnI, resulting in the shedding of AIS/ZnS QDs signal probe for signal "off" detection of MTase. This work opened a new photosensitized probe and developed a promising PEC biosensor for dual-targets assay. By programming the DNA nanostructure, the biosensor can detect versatile targets in a simple and sensitive method, which has good practical application value in human serum.

Synthesis and hybridization of CuInS2 nanocrystals for emerging applications

Copper indium sulfide (CuInS2) is a ternary A(I)B(III)X(VI)2-type semiconductor featuring a direct bandgap with a high absorption coefficient. In attempts to explore their practical applications, nanoscale CuInS2 has been synthesized with crystal sizes down to the quantum confinement regime. The merits of CuInS2 nanocrystals (NCs) include wide emission tunability, a large Stokes shift, long decay time, and eco-friendliness, making them promising candidates in photoelectronics and photovoltaics. Over the past two decades, advances in wet-chemistry synthesis have achieved rational control over cation-anion reactivity during the preparation of colloidal CuInS2 NCs and post-synthesis cation exchange. The precise nano-synthesis coupled with a series of hybridization strategies has given birth to a library of CuInS2 NCs with highly customizable photophysical properties. This review article focuses on the recent development of CuInS2 NCs enabled by advanced synthetic and hybridization techniques. We show that the state-of-the-art CuInS2 NCs play significant roles in optoelectronic and biomedical applications.

An insight of light-enhanced electrochemical kinetic behaviors and interfacial charge transfer of CuInS2/MoS2-based sensing nanoplatform for ultra-sensitive detection of chloramphenicol

Owing to the effective combination between MoS₂ sheets with CuInS₂ nanoparticles (NPs), a direct Z-scheme heterojunction was successfully constructed and proved as a promising structure to modify the working electrode surface with the aim of enhancing overall sensing performance towards CAP detection. Herein, MoS₂ was employed as a high mobility carrier transport channel with a strong photo-response, large specific surface area, and high in-plane electron mobility, while CuInS₂ acted as an efficient light absorber. This not only offered a stable nanocomposite structure but also created impressive synergistic effects of high electron conductivity, large surface area, highlight exposure interface, as well as favorable electron transfer process. Moreover, the possible mechanism and hypothesis of the transfer pathway of photo-induced electron-hole pairs on the CuInS₂-MoS₂/SPE as well as their impacts on the redox reaction of K₃/K₄ probes and CAP were proposed and investigated in detail via a series of calculated kinetic parameters, demonstrating the high practical applicability of light-assisted electrodes. Indeed, the detection concentration range of the proposed electrode was widened from 0.1 to 50 μM, compared with that of 1-50 μM without irradiation. Also, the LOD and sensitivity values were calculated to be approximately 0.06 μM and 0.4623 μA μM^-1, which is better than that of 0.3 μM and 0.095 μA μM^-1 without irradiation.

AgInZnS quantum dots as anodic emitters with strong and stable electrochemiluminescence for biosensing application

Quantum dots (QDs) have become promising electrochemiluminescence (ECL) emitters with high quantum yield and size-tunable luminescence. However, most QDs generate strong ECL emission at the cathode, developing anodic ECL-emitting QDs with excellent performance is challenging. In this work, low-toxic quaternary AgInZnS QDs synthesized by a one-step aqueous phase method were used as novel anodic ECL emitters. AgInZnS QDs exhibited strong and stable ECL emission and a low excitation potential, which could avoid the side reaction of oxygen evolution. Furthermore, AgInZnS QDs displayed high ECL efficiency (Φ_ECL) of 5.84, taking the Φ_ECL of Ru(bpy)₃²⁺/tripropylamine (TPrA) ECL system as 1. Compared to AgInS₂ QDs without Zn doping and traditional anode luminescent CdTe QDs, the ECL intensity of AgInZnS QDs was 1.62 times and 3.64 times higher than that of AgInS₂ QDs and CdTe QDs, respectively. As a proof-of-concept, we further designed an "on-off-on" ECL biosensor for detecting microRNA-141 based on a dual isothermal enzyme-free strand displacement reaction (SDR), which not only to achieve the cyclic amplification of the target and ECL signal, but also to construct a switch of the biosensor. The ECL biosensor had a wide linear range from 100 aM to 10 nM with a low detection limit of 33.3 aM. Together, the constructed ECL sensing platform is a promising tool for rapid and accurate diagnosis of clinical diseases.