High Visible Photoelectrochemical Activity of Ag Nanoparticle-Sandwiched CdS/Ag/ZnO Nanorods

Enhanced Photocatalytic Activity of V2C MXene-Coupled ZnO Porous Nanosheets with Increased Surface Area and Effective Charge Transfer

Photocatalysis performs excellently when degrading organic pollutants, but the photocatalytic degradation rate is not high for most photocatalysts due to their narrow sunlight adsorption range and high recombination rate of electron hole pairs. Herein, we use V2C-MXene with a wide sunlight adsorption range to couple ZnO porous nanosheets and form ZnO/MXene hybrids using a facile electrostatic self-assembly method. The ZnO/MXene hybrids acquired demonstrated improved photochemical efficiency in breaking down methylene blue (MB) when contrasted with porous ZnO nanosheets. The degradation rate of MB reached 99.8% under UV irradiation for 120 min after the ZnO/MXene hybrid formation, while 38.6% was attained by the ZnO porous nanosheets. Moreover, photodegradation rate constants (k) were calculated as 3.05 × 10-3 and 5.42 × 10-2 min-1 for ZnO porous nanosheets and ZnO/MXene hybrids, respectively, indicating that the photodegradation performance was enhanced by 17.8 times after the modification of V2C. This was probably because the modification of V2C can increase the specific surface area to provide more sites for MB adsorption, widen the sunlight adsorption range to produce good photothermal effect, and facilitate the transfer of photogenerated carriers in ZnO to promote the reaction of more photogenerated carriers with MB. Hence, this work offers a simple approach to creating effective photocatalysts for breaking down organic contaminants.

Highly sensitive and selective photoelectrochemical detection of bis(2-ethylhexyl)phthalate on broad-spectrum responsive and interfacial electronic interaction induced p-n BiOI/ZnO nanoarrays heterojunction

Bis(2-ethylhexyl)phthalate (DEHP), an endocrine disruptor, shows carcinogenic, teratogenic, mutagenic and estrogenic effects. It is easy to release from plastic materials and migrate to soil environment, causing serious pollution and posing a great threat to human health. In our work, a photoelectrochemical (PEC) sensing platform for DEHP detection was constructed using BiOI/ZnO nanoarrays (NRs) as the transducer species and the DEHP aptamers as the biological recognition elements. ZnO NRs with three-dimensional and large diameter area were prepared by hydrothermal method to increase the light absorption capacity. Coupling BiOI in a narrow band gap with ZnO NRs strengthened visible-light absorption, while promoting charge carrier separation and transportation. This was attributed to the generation of an internal electric field between BiOI and ZnO NRs, exhibiting obvious photocurrent response. The as-developed PEC sensing platform demonstrated great sensing performance for detection of DEHP. Furthermore, the photocurrent varied and the logarithm of DEHP concentration showed a linear relationship from 1.0 × 10-11 to 5.0 × 10-7 mol/L, and the limit of detection was estimated to be 3.8 × 10-12 mol/L. In the meantime, while evaluating its usage in real soil samples, satisfying outcomes were realized. Thus, the as-proposed PEC sensing platform provided a potential device to monitor DEHP in the environment.

Pyroelectric-Effect-Assisted Near-Infrared-Driven Photoelectrochemical Biosensor Based on Exponential DNA Amplifier for MicroRNA Detection

Although near-infrared responsive photoelectrochemical (PEC) biosensors have less damage to biological components compared to UV-visible light, they still reveal an inferior response due to the rapid recombination of photogenerated electron-hole. In this study, a near-infrared-driven PEC biosensor is fabricated for microRNA (miRNA) detection via integrating photoelectricity and pyroelectricity. Upon the introduction of target miRNA-21, the exponential DNA amplifier is triggered based on enzyme-assisted strand displacement amplification (SDA), releasing multiple Ag2S reporter probes to hybridize with capture probes immobilized on a CdS-2-mercaptobenzimidazole (2MBI)-modified photoelectrode. As a result, under the stimulation of NIR, the photoelectric conversion of Ag2S NPs generates the photocurrents. In addition, due to the strong hole acceptor ability of MBI, the pyroelectric effect of CdS-2MBI nanocomposites is enhanced, which generates highly pyroelectro-induced charge separation efficiency and induces the pyroelectric current benefited from the spontaneous polarization of CdS-2MBI caused by the temperature variation under the function of Ag2S nanoheaters. Impressively, this PEC biosensor has achieved the sensitive and selective determination of miRNA-21 with a detection limit as low as 54 fM. Overall, this NIR-driven PEC biosensor based on pyroelectric and photoelectric effects opens up a new horizon for bioanalysis and early disease diagnosis.

Dual-Photoelectrode Fuel Cell Based Self-Powered Sensor for a Picomole Level Pollutant: Using an In Situ Molecularly Imprinted p-Type Organic Photocathode

Developing a dual-photoelectrode fuel cell based self-powered sensor (DPFC-SPS) with an ideal signal output capability and high sensitivity performance for the detection of environmental pollutant atrazine (ATZ) has an important value. In this work, the in situ molecularly imprinting functionalized p-type organic semiconductor polyterthiophene (MI-pTTh) is used as a photocathode to construct a DPFC-SPS toward the typical environmental pollutant ATZ for the first time. Due to its excellent photoactivity, higher stability, and superior oxygen reduction reaction activity, pTTh serves as the photocathode material for constructing a self-powered sensing platform with a stable signal output and high photoelectric activity. Based on the sensitive light-triggered large self-bias of the DPFC-SPS, the open circuit potential (EOCV) of the device reaches 1.21 V and the maximum power density (Pmax) reaches 121.5 μW·cm-2, which is much higher than most reported PFC-SPSs. Simultaneously, in situ molecularly imprinted (MI) functionization of pTTh can further endow it with specific recognition ability, helping the constructed SPS achieve high sensitivity, selectivity, and effective recognition of the important environmental pollutants ATZ in complex systems. It exhibits a broad linear relationship from 0.002 to 100 nM and a low detection limit (estimated by S/N > 3) of 0.21 pM toward ATZ. The mechanism of the binding kinetics of the MI-pTTh with the target ATZ is further studied via in situ infrared spectroscopy. This work provides theoretical guidance for sensing strategies using dual-photoelectrode devices and offers a rational device design for cost-effective electricity generation from renewable resources.

CdSe@CdS quantum dot-sensitized Au/α-Fe2O3 structure for photoelectrochemical detection of circulating tumor cells

Circulating tumor cells (CTCs) are the important biomarker for cancer diagnosis and individualized treatment. However, due to the extreme rarity of CTCs (only 1-10 CTCs are found in every milliliter of peripheral blood) high sensitivity and selectivity are urgently needed for CTC detection. Here, a sandwich PEC cytosensor for the ultrasensitive detection of CTCs was developed using the photoactive material Au NP/-Fe₂O₃ and core-shell CdSe@CdS QD sensitizer. In the proposed  protocol, the CdSe@CdS QD/Au NP/α-Fe₂O₃-sensitized structure with cascade band-edge levels could evidently promote the photoelectric conversion efficiency due to suitable light absorption and efficient electron-hole pair recombination inhibition. Additionally, a dendritic aptamer-DNA concatemer was constructed for highly efficient capture of MCF-7 cells carrying CdSe@CdS QDs, a sensitive material. The linear range of this proposed signal-on PEC sensing method was 300 cell mL^-1 to 6 × 10⁵ cell mL^-1 with a detection limit of 3 cell mL^-1, and it demonstrated an ultrasensitive response to CTCs. Furthermore, this PEC sensor enabled accurate detection of  CTCs in serum samples. Hence, a promising strategy for CTC detection in clinical diagnosis was developed based on CdSe@CdS QD-sensitized Au NP/α-Fe₂O₃-based PEC cytosensor with dendritic aptamer-DNA concatemer.

Ultrathin Nanosheet-Supported Ag@Ag2O Core-Shell Nanoparticles with Vastly Enhanced Photothermal Conversion Efficiency for NIR-II-Triggered Photothermal Therapy

Photothermal therapy (PTT) working in the second near-infrared (NIR-II) region has aroused a huge interest due to its potential application in terms of clinical cancer treatment. However, owing to the lack of photothermal nanoagents with high photothermal conversion efficiency, NIR-II-driven PTT still suffers from poor efficiency and subsequent cancer recurrence. In this work, we show a new and highly efficient preparation approach for NIR-II photothermal nanoagents and tailor ultrathin layered double hydroxide (LDH)-supported Ag@Ag₂O core-shell nanoparticles (Ag@Ag₂O/LDHs-U), vastly improving NIR-II photothermal performance. A combination study (high-resolution transmission electron microscopy (HRTEM), extended X-ray absorption fine structure spectroscopy (EXAFS), and X-ray photoelectron spectroscopy (XPS)) verifies that ultrafine Ag@Ag₂O core-shell nanoparticles (∼3.8 nm) are highly dispersed and firmly immobilized within ultrathin LDH nanosheets, and their Ag₂O shell possesses abundant vacancy-type defects. These unique Ag@Ag₂O/LDHs-U display an impressive photothermal conversion efficiency as high as 76.9% at 1064 nm. Such an excellent photothermal performance is likely attributed to the enhanced localized surface plasmon resonance (LSPR) coupling effect between Ag and Ag₂O and the reduced band gap caused by vacancy-type defects in the Ag₂O shell. Meanwhile, Ag@Ag₂O/LDHs-U also show prominent photothermal stability, due to the unique supported core-shell nanostructure. Moreover, both in vitro and in vivo studies further confirm that Ag@Ag₂O/LDHs-U possess good biocompatible properties and outstanding PTT therapeutic efficacy in the NIR-II region. This research shows a new strategy in the rational design and preparation of an efficient photothermal agent, which is helpful to achieve more accurate and effective cancer theranostics.

Strategy to Achieve Augmented Photoelectrochemical Water Oxidation via Heteroband Structure Engineering and In Situ Interface Activation

A simple strategy to achieve remarkable activity of photoelectrochemical (PEC) water oxidation is both a critical requirement prior to accelerating the deployment of hydrogen and an important pursuit for renewable solar energy utilization. Despite various ways to improve the PEC performance, laborious fabrication and a statically driven process for water oxidation are still the most challenging tasks. We, herein, demonstrated an extremely simple but extraordinary effective strategy to boost PEC water splitting in a three-dimensional (3D) network structure (Ni foam, i.e., NF)-supported ZnO nanowire (NW)/CdS nanoparticle (NP) (NF/ZnO/CdS) photoelectrode. On the one hand, the establishment and optimization of a heteroband junction between ZnO NWs and CdS NPs substantially reduce the solar energy loss and increase the photocarrier utilization rate at the interface of two phases. On the other hand, the solution flow rotation in the unique macroporous 3D network structure gives rise to obvious piezoelectric (PE) polarization of ZnO located on the skeleton of Ni foam, which can dynamically enforce directional charge transfer. This real-time self-built PE polarization, assisted by the heteroband junction, enables the NF/ZnO/CdS photoanode system to obtain an improved photocurrent density by 12.2-fold compared with pure ZnO (at 1.23 V vs RHE). This work sheds light on an ingenious design strategy for fabricating photoelectrodes that combines a simplified structure and an effectively enhanced water oxidation performance.

Bioinspired Synthesis of ZnO@polydopamine/Au for Label-Free Photoelectrochemical Immunoassay of Amyloid-β Protein

Amyloid-β protein (Aβ) is an important biomarker and plays a key role in the early stage of Alzheimer's disease (AD). Here, an ultrasensitive photoelectrochemical (PEC) sensor based on ZnO@polydopamine/Au nanocomposites was constructed for quantitative detection of Aβ. In this sensing system, the ZnO nanorod array decorated with PDA films and gold nanoparticles (Au NPs) have excellent visible-light activity. The PDA film was used as a sensitizer for charge separation, and it also was used for antibody binding. Moreover, Au NPs were loaded on the surface of PDA film by in situ deposition, which further improved the charge transfer efficiency and the PEC activity in visible light due to the localized surface plasmon resonance effect of Au NPs. Therefore, in ZnO@polydopamine/Au nanocomposites, a significantly enhanced photocurrent response was obtained on this photoelectrode, which provides a good and reliable signal for early detection of AD. Under the optimized conditions, the PEC immunosensor displayed a wide linear range from 1 pg/mL to 100 ng/mL and a low detection limit of 0.26 pg/mL. In addition, this PEC immunosensor also presented good selectivity, stability, and reproducibility. This work may provide a promising point-of-care testing method toward advanced PEC immunoassays for AD biomarkers.

Construction of Bi2MoO6/CdS heterostructures with enhanced visible light photocatalytic activity for fuel denitrification

In this work, a novel step-scheme (S-scheme) Bi₂MoO₆/CdS heterojunction (HJ) photocatalyst (PC) was successfully prepared by a two-step solvothermal method for the first time. One-dimensional CdS nanorods were prepared by a simple solvothermal method as a synthesis template. Then, a Bi₂MoO₆ precursor was added to obtain a series of Bi₂MoO₆/CdS HJ composite catalytic materials with different morphologies. The photocatalytic performance of the catalyst was investigated by simulating fuel denitration as a probe reaction under visible light excitation (>420 nm). When compared with pure Bi₂MoO₆ and CdS, the 0.65-Bi₂MoO₆/CdS composite shows the highest photocatalytic activity for pyridine degradation. Degradation of pyridine reached 81% after 240 min of visible light excitation. The degradation rate of 0.65-Bi₂MoO₆/CdS reached 0.4471 h^-1, which was 1.8 and 3.2 times higher than that of CdS (0.2493 h^-1) and Bi₂MoO₆ (0.1427 h^-1), respectively. Combined with a series of characterisation results, the improvement in pyridine degradation activity was mainly attributed to (1) the S-scheme HJ structure between Bi₂MoO₆ and CdS, which greatly promoted the separation of photogenerated electrons and holes while retaining its strong redox ability, (2) the large specific surface area, which provided abundant active sites and efficient adsorption performance and catalytic performance, and (3) the special morphology, which induced multiple reflections of light, thereby improving absorption and utilisation of light. Moreover, after four cycles of pyridine denitrification, the samples still exhibited high activity, indicating good stability and recyclability of the composite catalyst. These findings provide a basis for the development of composite PCs for efficient fuel denitration under visible light irradiation.

Fabrication, characterization and photoelectrochemical properties of CdS/CdSe nanofilm co-sensitized ZnO nanorod arrays on Zn foil substrate

The photoelectrochemical (PEC) performance of ZnO is restricted by its low light absorption ability and high recombination rate of photogenerated carriers. In order to overcome these drawbacks, ZnO/CdS/CdSe heterostructures are prepared on Zn foil substrate using facile three-step methods containing hydrothermal growth, successive ionic layer adsorption reaction (SILAR) and modified chemical bath deposition (CBD). The effects of process parameters containing the number of SILAR cycles of CdS, sensitization sequence of CdS and CdSe, and precursors of CdSe on PEC performance of ZnO/CdS/CdSe heterostructures, and ZnO NRAs on PEC performance of CdS/CdSe co-sensitizer have been scrutinized. Through CdS and CdSe co-sensitization, a layer of CdS/CdSe nanofilm is conformally deposited on ZnO nanorod arrays (NRAs) observed by transmission electron microscopy (TEM). Both the visible-light absorption ability and separation efficiency of photogenerated carriers of ZnO NRAs are significantly enhanced evidenced by UV-vis diffuse reflectance absorption spectra, photoluminescence (PL) spectra and electrochemical impedance spectra. Due to the synergistic effect of ZnO NRAs and CdS/CdSe co-sensitizer, the ZnO/CdS/CdSe heterostructures with five SILAR cycles and one modified CBD cycle (ZnO-CdS5-CdSe) show efficient PEC properties with photocurrent density of 6.244 mA/cm² at -0.2 V vs Ag/AgCl under light illumination of 100 mW/cm², which are 57.28 and 4.73 times higher than those of pristine ZnO NRAs and CdS/CdSe clusters, respectively. Moreover, the photoconversion efficiency and incident photon to current conversion efficiency (IPCE) of the ZnO-CdS5-CdSe photoanode reach 4.381% and 80.92%, respectively. The heterostructures based on Zn foil substrate in this study can be a promising candidate for practical PEC application and other applications such as photocatalytic degradation and solar cell due to its low manufacturing cost, large-scale production and efficient PEC ability.

A photoanode with plasmonic nanoparticles of earth abundant bismuth for photoelectrochemical reactions

A wide range of technologies has been developed for producing hydrogen economically and in greener ways. Photoelectrochemical water splitting using photoelectrodes submerged in a bath electrolyte forms a major route of hydrogen evolution. The efficacy of water splitting is improved by sensitizing metal oxide photoelectrodes with narrow bandgap semiconductors that efficiently absorb sunlight and generate and transport charge carriers. Here we show that the efficiencies of photocurrent generation and photoelectrochemical hydrogen evolution by the binary TiO₂/Sb₂S₃ anode increase by an order of magnitude upon the incorporation of the earth-abundant plasmonic bismuth nanoparticles into it. The ternary electrode TiO₂/Bi nanoparticle/Sb₂S₃ illuminated with sunlight provides us with a photocurrent density as high as 4.21 mA cm^-2 at 1.23 V, which is fourfold greater than that of the binary electrode and tenfold greater than that of pristine TiO₂. By using bismuth nanoparticles, we estimate the incident photon to current conversion efficiency at 31% and solar power conversion efficiency at 3.85%. Here the overall impact of bismuth nanoparticles is attributed to increases in the open-circuit voltage (860 mV), which is by expediting the transfer of photogenerated electrons from Sb₂S₃ nanoparticles to the TiO₂ electrode, and short-circuit current (9.54 mA cm^-2), which is by the plasmonic nearfield effect. By combining the cost-effective plasmonic bismuth nanoparticles with the narrow bandgap Sb₂S₃ on the TiO₂ electrode, we develop a stable, ternary photoanode and accomplish high-efficiency photocurrent generation and hydrogen evolution.

Core-shell structured cadmium sulfide nanocomposites for solar energy utilization

Solar energy utilization technologies have been widely explored to solve the global energy crisis because the inexhaustible solar energy can be converted into chemical fuel and electricity. Various semiconductors that are crucial for solar energy utilization have been extensively developed. Among them, cadmium sulfide (CdS) has attracted extensive attention due to its suitable band-gap and excellent electrical/optical properties. However, CdS is still limited by rapid charge recombination, instability and low quantum efficiency. Core-shell structures can provide great opportunities for constructing advanced structures with superior properties to overcome the remaining challenges. This review focuses on the significant advances in core-shell structured CdS nanocomposites for solar energy utilization. Initially, the synthetic methods to construct core-shell structured CdS nanocomposites are reviewed. Then the applications in solar energy utilization are discussed, including photocatalytic\photoelectrochemical water splitting, photocatalytic CO₂ reduction and solar cells. Finally, the perspectives of core-shell structured CdS nanocomposites for solar energy utilization are proposed.

The Potential of Pandanus Amaryllifolius Leaves Extract in Fabrication of Dense and Uniform ZnO Microrods

Zinc oxide (ZnO) micro and nanorods were successfully prepared using Pandanus amaryllifolius and hexamethylenetetramine (HMTA) separately as stabilizers using the solution immersion method. Two types of ZnO seed layer were prepared using the same pre-cursor with the different stabilizers. The fabricated ZnO microrods exhibit absorption at ~375 nm as revealed from the UV-Visible absorption spectrum, and this is comparable with ZnO nanorods synthesized using HMTA. X-ray diffraction (XRD) measurement displayed a sharp peak corresponding to the hexagonal wurtzite structure of ZnO microrods. Field emission scanning electron microscopy (FESEM) of ZnO microrods showed average diameter at approximately 500 nm compared to 70 nm of those synthesized from HMTA. A new finding is the ability of Pandanus amaryllifolius as a green stabilizer to grow a dense ZnO microrod structure with high crystallinity. Results reveal that both samples from different stabilizers during the preparation of the ZnO seed layer greatly improved the morphological and structural properties and optical absorption of ZnO. The main outcomes from this study will benefit optoelectronic application, such as in ultraviolet (UV) sensors.

Omnidirectional Au-embedded ZnO/CdS core/shell nanorods for enhanced photoelectrochemical water-splitting efficiency

The charge transfer mechanism that enhanced the photoconversion efficiency of omnidirectional Au-embedded ZnO/CdS core/shell nanorods.

Construction of a Z-Scheme Dictated WO3-X /Ag/ZnCr LDH Synergistically Visible Light-Induced Photocatalyst towards Tetracycline Degradation and H2 Evolution

Herein, we have designed nonstoichiometric WO₃, coupled with ZnCr layered double hydroxide (LDH) nanosheeet through Ag nanoparticle as the solid-state electron mediator to form WO_3-X /Ag/ZnCr LDH Z-scheme photocatalyst. The presence of oxygen defect levels in as-synthesized materials was confirmed by Raman, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) analyses. The photocatalytic performance of the catalysts was investigated by the tetracycline degradation and H₂ energy production under visible light irradiation. The WO_3-X /Ag/ZnCr LDH ternary heterostructure exhibits superior activity toward tetracycline degradation and hydrogen evolution. The excellent photocatalytic performance of the catalyst was attributed to the synergistic effects among three species (WO_3-X , Ag, and ZnCr LDH) and the enhanced separation efficiency of photoinduced charge carriers through the Z-scheme WO_3-X /Ag/ZnCr LDH system. In addition, the created oxygen deficiency on WO_3-X could improve the photocatalytic behavior of ZnCr LDH in heterostructure by delaying the recombination efficiency of photoexcited electron-hole pairs. Furthermore, the higher affinity of tetracycline at the oxygen defect levels of the photocatalyst supports the high rate of tetracycline degradation. The enhanced photocatlytic activity of the catalysts was further supported by PL spectra and photoelectrochemical studies (electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) plot). The present research opens up a new strategy for designing highly efficient visible light-induced Z-scheme-based photocatalysts with high population of active sites for energy and environmental applications in a sustainable manner.

ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation

Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag₂WO₄ heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag₂WO₄ photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag₂WO₄ was deposited on the ZnO NRs. The Ag₂WO₄/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag₂WO₄/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag⁰) particles from the Ag/Ag₂WO₄ that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag₂WO₄/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag₂WO₄ heterostructure with SPR effect for water oxidation.

Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications.

Modification strategies for enhancing the visible light responsive photocatalytic activity of the BiPO4nano-based composite photocatalysts

The present issues related to environmental purification have led to a great need for the development of a superior oxidation process to solve the life-threatening problem. The use of the BiPO₄nanomaterial in photocatalysis is one of the best methods for the treatment of wastewater due to its less harmful nature.

An amplification label of core–shell CdSe@CdS QD sensitized GO for a signal-on photoelectrochemical immunosensor for amyloid β-protein

Core–shell CdSe@CdS QDs conjugated with GO can enhance the photocurrent intensity.

Construction of Al-ZnO/CdS photoanodes modified with distinctive alumina passivation layer for improvement of photoelectrochemical efficiency and stability

ZnO/CdS-based nanorod arrays (NRs) are an excellent class of photoanode materials, which possess high photoelectric response for solar-driven water splitting. A highly efficient photoanode system consisting of Al-doped ZnO NRs as effective electron-transfer layers and CdS as a light harvesting layer was rationally designed. Al doping increased the conductivity of ZnO NRs and simultaneously coarsened the surface of ZnO due to expansion of ZnO lattice. The rough surface favoured the growth of a CdS coating layer on it through a successive ionic layer adsorption reaction. The integrated ZnO/CdS photoanode exhibited photocurrent of 10.4 mA cm^-2 at 1.23 V versus RHE (reversible hydrogen potential) and conversion efficiency of 5.75% at 0.38 V versus RHE for 60 SILAR CdS cycles. The coating of a protective Al₂O₃ passivation layer through the direct current magnetron sputtering technique significantly improved the stability of the electrode, and it was better than that of the conventional atomic layer deposition method.

Visible light-enhanced thermal decomposition performance of ammonium perchlorate with a metal–organic framework-derived Ag-embedded porous ZnO nanocomposite

An Ag-embedded porous ZnO nanocomposite (Ag–ZnO NC) fabricated using an MOF exhibits high catalytic activity for the thermal decomposition of AP under the assistance of visible light.

Controlled Synthesis of CeO2NS-Au-CdSQDs Ternary Nanoheterostructure: A Promising Visible Light Responsive Photocatalyst for H2 Evolution

With the advancement of promising multifaceted powdered photocatalytic systems, problems related to environmental pollution and energy requirements have been addressed to a significant extent. The major reason for this great achievement lies in the combined effect of both structure modification and integration of different functional materials. Here, we report a ternary hybrid containing wide band gap CeO₂ nanosheets with CdSQDs and Au nanoparticles, incorporated between this type II heterostructure through simple chemical reduction methods. Structural and morphological characterization of the fabricated samples was carried out by XRD, XPS, and TEM analysis. From a series of optical and photoelectrochemical measurements, it was found that the incorporation of Au nanoparticles into the interfaces of CeO₂ and CdSQDs was the major cause of the enhancement in the photocatalytic activity. Au nanoparticles play a dual character by acting as a mediator and also inject hot electrons through LSPR (light-induced surface plasmon resonance) effects in the ternary hybrid. The photocatalytic activity of the fabricated samples was tested toward H₂ evolution, where the ternary hybrid CeO₂NS-Au-CdSQDs lead the activity sequence with 499 μmol/2 h followed by the binary and neat counterparts. From the Mott-Shottky and linear sweep voltammetry measurements, a heterostructure relay mechanism was predicted where electrons from CdSQDs flow to the surface of CeO₂ via Au. The novelty of this work is that it provides useful information about the synergistic effect among three functional components, integrated in a nanosheet structured system, as the basic requirement for constructing good heterostructures in powdered photocatalytic systems.

Photoelectrochemical sensitive detection of insulin based on CdS/polydopamine co-sensitized WO3 nanorod and signal amplification of carbon nanotubes@polydopamine

An ultrasensitive photoelectrochemical sandwich immunosensor was designed for detection of insulin based on WO₃/CdS/polydopamine (WO₃/CdS/PDA) co-sensitized and PDA@carbon nanotubes (PDA@CNT) conjugates for signal amplification. The CdS nanoparticles were first deposited on the WO₃ nanorods via sequential chemical bath deposition to form the WO₃/CdS structure to enhance photocurrent. Then equipped with PDA to form the WO₃/CdS/PDA photosensitive structure. The PDA was used not only to reduce the toxicity of CdS but also adsorb insulin primary antibodies (Ab₁). Meanwhile, insulin secondary antibodies (Ab₂) were decorated by PDA@CNT conjugates for signal amplification and further enhance photocurrent. Different photocurrent intensities were obtained by the photoelectrochemical workstation at applied bias of 0V due to the different amount of the PDA@CNT conjugates introduced by the different concentrations of insulin. A good linear relationship was obtained between the increased photocurrent and insulin concentrations range from 0.01ngmL^-1 to 50ngmL^-1. And a detection limit of 2.8pgmL^-1 was obtained. The proposed sensor was applied to the determination of the insulin in human serum sample, and satisfactory results were obtained. The sensor presented good specificity, reproducibility and stability, thus it might find application in the clinical diagnosis of insulin or other biomarkers in the near future.

Fabrication of In2O3/ZnO@Ag nanowire ternary composites with enhanced visible light photocatalytic activity

Well-dispersed In₂O₃/ZnO nanoparticles covered Ag nanowires ternary component was synthesized by a facile co-precipitation process and exhibited excellent visible light photocatalytic performance.