Initial Photocurrent Research Articles

CRISPR/Cas13a-Programmed Cu NCs and Z-Scheme T-COF/Ag2S for Photoelectrochemical Biosensing of circRNA.

Circular RNAs (circRNAs), as a class of noncoding RNA molecules with a circular structure exhibit high stability and spatiotemporal-specific expression, making them ideal cancer biomarkers for liquid biopsy. Herein, a new photoelectrochemical (PEC) biosensor for a highly sensitive circRNA assay in the whole blood of lung cancer patients was designed based on CRISPR/Cas13a-programmed Cu nanoclusters (Cu NCs) and a Z-scheme covalent organic framework/silver sulfide (T-COF/Ag2S) composite. This Z-scheme T-COF/Ag2S composite accelerates electron transfer and produces an excellent initial photocurrent. When CRISPR/Cas13a precisely targets circRNA, it nonspecifically cleaves the triple-helix molecular structure to release DNA fragments (C'/C"). After the C'/C" opens the DNA hairpin probe (HP) modified on the electrode, hybridization chain reactions are performed to produce abundant AT-rich double-stranded DNA with the addition of H1 and H2 probes. Upon the incubation of Cu2+, Cu NCs are in situ formed via the A-Cu2+-T bonds and can effectively quench the photocurrent of the Z-scheme T-COF/Ag2S due to the energy transfer process. This developed PEC biosensor for the circRNA assay shows a low limit of detection of 0.5 fM, and the reusability of DNA-modified magnetic beads (MB-DNA) reduces the detection cost. Moreover, the PEC biosensor can accurately quantify the circRNA level and distinguish the circRNA expression in whole blood from healthy controls and lung cancer patients, offering strong potential in clinical diagnosis.

Colloidal Design and Preparation of an Internal Electric Modulated Z-Scheme BiOI-CdS Heteronanostructure with Oxygen-Rich Vacancies.

Photoelectrochemical (PEC) water splitting offers an ideal strategy for the development of clean and renewable energy. However, its practical implementation is often inhibited by the high recombination rate of photogenerated charge carriers and the instability of photoanodes. Introducing defect engineering (such as oxygen vacancies) and constructing internal electric field-modulated Z-scheme heteronanostructures (HNs) can be considered as effective approaches to overcome these obstacles. Herein, a flexible method is developed for synthesizing Z-scheme BiOI-CdS HNs with oxygen vacancies, which induce an internal electric field between ultrathin BiOI nanosheets and a CdS semiconductor. This Z-scheme mechanism significantly promotes the separation of photogenerated electron-hole pairs, thereby enhancing the PEC performance. The BiOI-CdS photoanode achieves a photocurrent density of 4.22 mA cm-2 at 1.6 V vs RHE under AM 1.5G illumination (100 mW cm-2), outperforming bare BiOI and CdS. Moreover, the photoanode exhibits exceptional stability with only a slight decrease of approximately in its initial photocurrent after a rigorous 4 h test, surpassing other counterparts in terms of durability. This work affords a better understanding of oxygen vacancies and the construction of highly efficient and stable Z-scheme photoanodes for feasible PEC application.

Synergistic Doping Strategy with Novel Multi-Carbonyl Conductive Polymer Enables Stable Self-Powered Perovskite Photodetectors.

Lead halide perovskites hold immense promise for optoelectronic applications but still suffer from instability caused by defects. The defects are mainly generated from the film fabrication processes and halide ion migration during long-term storage. Here, a synergistic doping strategy is proposed to enhance the stability of perovskites. A novel multi-carbonyl conductive polymer, poly(benzodifurandione) (PBFDO), is incorporated into the precursor solution to effectively passivate the unoccupied Pb2+ defects in perovskite films and promote the continuous growth of perovskites. An organic iodide, thiophene-2-ethylammonium iodide (TEAI), is doped in the transport layer to inhibit the halide ion migration and enhance the stability of perovskites synergistically. Self-powered photodetectors are constructed with improved stability, maintaining ≈90% of their initial photocurrents after being stored for ≈87 days in a humid atmosphere with 60% relative humidity. The optimized photodetectors show a high detectivity of 8.1×1012 Jones at 680 nm wavelength, wide linear dynamic range of 121.9 dB, and fast response with a rise/fall time of 1.92/1.17µs. A reflection-mode perovskite photoplethysmography testing system is developed, achieving high heart rate testing capabilities. This work suggests the great potential of perovskite photodetectors for noninvasive medical monitoring applications.

Enhanced photoelectric desalination of Co3O4@NC/BiVO4 photoanode via in-situ construction of hole transport layer

The solar-driven photoelectrochemical desalination (SD-PED) technology, as a new emerging desalination technique, has been developed and attracted the increasing attention. However, practical application remains hampered by several constraints, including the rapid deterioration of photocurrent, and the long-term stability of system. In this research, MOF-derived nitrogen-doped carbon@Co3O4/BVO (Co3O4@NC/BVO) heterostructured photoanode was design for efficient and durable solar driven redox desalination. It exhibits an initial photocurrent of 2.40 mA/cm2 and a desalination rate of 69.01 μg/(cm2·min) in the zero-bias state using the light as the driving force, without consuming electrical energy. Furthermore, the solar energy consumption of the photoanode is 0.187 μmol/J. The salt removal rate fluctuates within 1.36 μg/(cm2·min) throughout five cycles without any substantial decrease. Photo-luminescence, EIS and Mott-Schottky analysis are also performed to investigate interface reaction, charge separation and transfer mechanism between photoanode and electrolyte. The analysis of the charge-transfer paths on the heterojunction interface is conducted through in situ irradiation XPS. Further analysis of the generation and separation of •OH and h+ in the Co3O4@NC/BVO photoanode using electron paramagnetic resonance (EPR) showed that Co3O4@NC as an efficient hole transfer layer can effectively promote the separation and transfer of photo-generated electrons and holes. The excellent desalination performance is attributed to the synergistic effect of electron transfer in the Co3O4@NC/BVO heterojunction and hole transport in the Co3O4@NC efficient hole transport layer. This work is significant for the development of solar redox flow desalination.

Centimeter‐Scale and Honeycomb‐Like Bismuth Sulfide Film Composed of Triangular Structural Units for Flexible Photodetector

AbstractFilms with honeycomb‐like structures have became ideal network structures for the development of flexible photodetectors due to their superior mechanical stability and merits in large active surface area, high carrier transport efficiency and well light absorption capacity. In this work, a honeycomb‐like Bi2S3 film with centimeter‐scale (2 cm × 2 cm) is synthesized on an ultrathin flexible fluorophlogopite mica substrate, which consists of a well‐stabilized arrangement of triangular unit structures forming an interconnected network structure. Based on the as‐grown honeycomb‐like Bi2S3 film, a flexible photodetector with a broadband response from ultraviolet to infrared is constructed, which displays the highest responsivity (Rλ) of 611.2 mA W−1 and specific detectivity (D*) of 4.77 × 1010 Jones. And at 850 nm light illumination, there is nearly no deterioration in Rλ and D* of the Bi2S3 flexible photodetector after successive multiple bends, benefiting from the excellent structural stability of the triangular honeycomb network structure. Notably, the device maintains excellent detection performance after 1 week of prolonged bending in air without any encapsulation, and its photocurrent can still reach 90.39% of the initial photocurrent. In addition, the device also exhibits favorable durability, cycle stability, as well as high‐definition imaging ability in bending state and after bending recovery.

Ultrahigh Responsivity and Robust Semiconducting Fiber Enabled by Molecular Soldering-Governed Defect Engineering for Smart Textile Optoelectronics.

Semiconducting fibers (SCFs) are of significant interest to design next-generation wearable and comfortable optoelectronics that seamlessly integrate with textiles. However, the practical applications of current SCFs are always limited by poor optoelectronic performance and low mechanical robustness caused by uncontrollable multiscale structural defects. Herein, a versatile in situ molecular soldering-governed defect engineering strategy is proposed to construct ultrahigh responsivity and robust wet-spun MoS2 SCFs, by using a π-conjugated dithiolated molecule to simultaneously patch microscale sulfur vacancies within MoS2 nanosheets, diminish mesoscale interlayer voids/wrinkles, promote macroscale orientation, build long-range photoelectron percolation bridges, and provide n-doping effect. The derived MoS2 SCFs exhibit over two orders of magnitude higher responsivity (144.3 A W-1) than previously reported fiber photodetectors, 37.3-fold faster photoresponse speed (52ms) than pristine counterpart, and remarkable bending robustness (retain 94.2% of the initial photocurrent after 50000 bending-flattening cycles). Such superior robustness and photodetection capacity of MoS2 SCFs further enable large-scale weaving of reliable smart textile optoelectronic systems, such as direction-identifiable wireless light alarming system, modularized mechano-optical communication system, and indoor light-controlled IoT system. This work offers a universal strategy for the scalable production of mechanically robust and high-performance SCFs, opening up exciting possibilities for large-scale integration of wearable optoelectronics.

Graphene-Perovskite Fibre Photodetectors.

The integration of optoelectronic devices, such as transistors and photodetectors (PDs), into wearables and textiles is of great interest for applications such as healthcare and physiological monitoring. These require flexible/wearable systems adaptable to body motions, thus materials conformable to non-planar surfaces, and able to maintain performance under mechanical distortions. Here, fibre PDs are prepared by combining rolled graphene layers and photoactive perovskites. Conductive fibres (~500 Ωcm-1) are made by rolling single-layer graphene (SLG) around silica fibres, followed by deposition of a dielectric layer (Al2O3 and parylene C), another rolled SLG as a channel, and perovskite as photoactive component. The resulting gate-tunable PD has a response time~9ms, with an external responsivity~22kAW-1 at 488nm for a 1V bias. The external responsivity is two orders of magnitude higher, and the response time one order of magnitude faster, than state-of-the-art wearable fibre-based PDs. Under bending at 4mm radius, up to~80% photocurrent is maintained. Washability tests show~72% of initial photocurrent after 30 cycles, promising for wearableapplications.

Photocurrent polarity switching photoelectrochemical aptasensor for oxytetracycline based on BiOBr/Ag2S/PDA//CuO: CuO-induced II-type to dual Z-scheme system

BackgroundAs a broad-spectrum tetracycline antibiotic, Oxytetracycline (OTC) was widely used in a variety of applications. But, the overuse of OTC had led to the detection of it in food, water and soil, which could present significance risk to human health and cause damage to ecosystem. It was of great significance to develop sensitive detection methods for OTC.Herein, an environmentally friendly photoelectrochemical (PEC) aptasensor was constructed for the sensitive detection of OTC based on CuO-induced BiOBr/Ag2S/PDA (Polydopamine) photocurrent polarity reversal. ResultsBiOBr/Ag2S/PDA composites modified electrode not only produced stable initial anodic photocurrent but also provided attachment sites for the aptamer S1 of OTC by the strong adhesion of PDA. On the other hand, CuO loaded OTC aptamer S2 (Cu–S2) was got through Cu–S bonds. After the target OTC was identified on the electrode surface, CuO was introduced to the surface of ITO/BiOBr/Ag2S/PDA through the specific binding of OTC to S2. This identification process formed dual Z-type heterojunctions and resulted in a remarkable reversal of photocurrent polarity from anodic to cathodic. Under optimization conditions, the PEC aptasensor showed a wide linear range (50 fM ∼ 100 nM), low detection limit (1.9 fM), excellent selectivity, stability and reproducibility for the detection of OTC. Moreover, it was successfully used for the analysis of OTC in real samples of tap water, milk and honey, and had the potential for practical application. SignificanceThis work developed an environmentally friendly photocurrent-polarity-switching PEC aptasensor with excellent selectivity, reproducibility, stability, low LOD and wide linear range for OTC detection. This sensitive system, which was including BiOBr, Ag2S, PDA and CuO were low toxicity, not only reduced the risk of traditional toxic semiconductors to operators and the environment, but can also be used for the detection of real samples, broadening the wider range of applications for BiOBr, Ag2S, PDA and CuO.

Cu2O/CuO composite for efficient performance in photoelectrochemical and optoelectronics applications

This study introduces a highly active photoelectrode, comprising a Cu2O/CuO composite, synthesized through annealing Cu2O thin film under controlled conditions to induce partial oxidation. Through systematic investigation of annealing conditions, including temperature and duration, an optimal synthesis condition of 400 °C for 1 h was identified, resulting in superior photoelectrochemical and optoelectronic properties. It yielded the most favorable outcomes, exhibiting the largest charge carrier density of 1.09 × 1021 cm−3, lowest charge transfer resistance of 18.8 Ω, and highest photocurrent density of −2.97 mA cm−2 with stability of 81%. This performance enhancement, which surpassed the initial photocurrent by 7 times under AM 1.5 simulated sunlight illumination at 0 V versus the reversible hydrogen electrode (RHE), is attributed to the formation of the Cu2O/CuO composite. This composite facilitates improved electron-hole pair separation efficiency, while the narrow bandgap of CuO enables enhanced light absorption. Additionally, the stability of the photocurrent is significantly improved by 2.3 times, attributed to the protective function of the CuO layer on Cu2O. Thus, the Cu2O/CuO composite emerges as a highly efficient and promising photocathode, offering a facile and cost-effective route for photoelectrochemical and optoelectronics applications.

Ultrastable halide perovskite CsPbBr3 photoanodes achieved with electrocatalytic glassy-carbon and boron-doped diamond sheets

Halide perovskites exhibit exceptional optoelectronic properties for photoelectrochemical production of solar fuels and chemicals but their instability in aqueous electrolytes hampers their application. Here we present ultrastable perovskite CsPbBr3-based photoanodes achieved with both multifunctional glassy carbon and boron-doped diamond sheets coated with Ni nanopyramids and NiFeOOH. These perovskite photoanodes achieve record operational stability in aqueous electrolytes, preserving 95% of their initial photocurrent density for 168 h of continuous operation with the glassy carbon sheets and 97% for 210 h with the boron-doped diamond sheets, due to the excellent mechanical and chemical stability of glassy carbon, boron-doped diamond, and nickel metal. Moreover, these photoanodes reach a low water-oxidation onset potential close to +0.4 VRHE and photocurrent densities close to 8 mA cm−2 at 1.23 VRHE, owing to the high conductivity of glassy carbon and boron-doped diamond and the catalytic activity of NiFeOOH. The applied catalytic, protective sheets employ only earth-abundant elements and straightforward fabrication methods, engineering a solution for the success of halide perovskites in stable photoelectrochemical cells.

Photoelectrochemical Sensor for H2S Based on a Lead-Free Perovskite/Metal-Organic Framework Composite.

Halide perovskites have emerged as a highly promising class of photoelectric materials. However, the application of lead-based perovskites has been hindered by their toxicity and relatively weak stability. In this work, a composite material comprising a lead-free perovskite cesium copper iodide (CsCu2I3) nanocrystal and a metal-organic framework (MOF-801) has been synthesized through an in situ growth approach. The resulting composite material, denoted as CsCu2I3/MOF-801, demonstrates outstanding stability and exceptional optoelectronic characteristics. MOF-801 may serve a dual role by acting as a protective barrier between CsCu2I3 nanocrystals and the external environment, as well as promoting the efficient transfer of photogenerated charge carriers, thereby mitigating their recombination. Consequently, CsCu2I3/MOF-801 demonstrates its utility by providing both stability and a notably high initial photocurrent. Leveraging the inherent reactivity between H2S and the composite material, which results in the formation of Cu2S and structural alteration, an exceptionally sensitive photoelectrochemical sensor for H2S detection has been designed. This sensor exhibits a linear detection range spanning from 0.005 to 100 μM with a remarkable detection limit of 1.67 nM, rendering it highly suitable for precise quantification of H2S in rat brains. This eco-friendly sensor significantly broadens the application horizon of perovskite materials and lays a robust foundation for their future commercialization.

High performance photoelectrochemical immunosensing platform based on front-illuminated Mo:BiVO4 photoelectrodes for procalcitonin assay

The outstanding photoactive materials are the imperative for the construction of a front-illuminated photoelectrochemical (PEC) biosensor, which is crucial step for improving the detection sensitivity. Yet, the weak and unstable initial PEC signals of the photoelectrodes have limited evidently the detection performance. Herein, a front-illuminated “on-off” PEC immunosensor was constructed based on Mo:BiVO4 as photoactive matrix and Au/CeO2 as signal quencher for sensitive detection of procalcitonin (PCT). Systematic studies reveal that the Mo doped BiVO4 can increase the charge carrier density of BiVO4, leading to much higher initial signal under front illumination than back illumination. Moreover, Mo:BiVO4 was directly grown on conducting substrates, which effectively overcomes the loose combination of sensing substrate ensuring good electrical contact and continuity. Upon coupling with Au/CeO2 as signal quencher, the initial photocurrent signal can be significantly quenched. As a result, the proposed PEC immunosensor presents a wide linear range from 10 fg mL−1 to 50 ng mL−1 with a detection limit of 2.45 fg mL−1. Impressively, this study will open a new avenue for the construction of highly efficient and stable photoelectrode, as well as extend the application of PEC biosensor for biomarkers detection in early disease diagnosis.

Efficient sensitization of CdTe QDs towards PTCDA for sensitive photoelectrochemical Hg2+ assay.

Herein, a sensitive photoelectrochemical (PEC) biosensor was designed for the detection of mercury ions (Hg2+) on the basis of the efficient sensitization of cadmium telluride quantum dots (CdTe QDs) towards 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and the significant quenching ability of a thymine-Hg2+-thymine (T-Hg2+-T) structure. The proposed CdTe QD/PTCDA sensitized structure was successfully constructed via continuous incubation of PTCDA and CdTe QDs on the glassy carbon electrode (GCE) interface, which embraced strong light absorption capacity and high carrier separation efficiency, giving rise to a remarkably improved initial photocurrent response. Notably, the PEC signal generated from the CdTe QD/PTCDA sensitized structure was almost fivefold higher than that of PTCDA owing to the efficient sensitization of CdTe QDs towards PTCDA. Once target Hg2+ ions were added, a T-rich S1 strand modified on the surface of 1-hexanethiol (HT)/S1/gold nanoparticles (Au NPs)/CdTe QDs/PTCDA/GCE immediately reacted with Hg2+ to produce multiple stable T-Hg2+-T structures. Therefore, the initial PEC signal would be considerably quenched by a high steric hindrance effect derived from the T-Hg2+-T structures. As a result, a quenched PEC response could achieve the detection of Hg2+ in concentrations ranging from 100 fM to 1000 nM. More importantly, the combination of the CdTe QDs/PTCDA sensitization structure and the T-Hg2+-T structure paves a promising pathway to developing a novel PEC biosensing platform for Hg2+ detection and also provides a favorable strategy for monitoring environmental pollution related to Hg2+.

2D Z-scheme ZnIn2S4/g-C3N4 heterojunction based on photoelectrochemical immunosensor with enhanced carrier separation for sensitive detection of CEA

Semiconducting materials based on photoelectrochemical (PEC) sensors have been widely utilized for detection. Meanwhile, the sensitivity of the PEC sensor was limited by low-efficiency carrier separation. Thus, a novel sandwich-type PEC bioimmunosensing based on 2D Z-scheme ZnIn2S4/g-C3N4 heterojunction as a photosensitive material and BiVO4 as a photoquencher was designed for the sensitive detection of carcinoembryonic antigen (CEA). Firstly, the 2D ZnIn2S4/g-C3N4 structure provided a multitude of activated sites which facilitated the loading of the capture antibody (Ab1). Secondly, the Z-scheme heterojunction had a high redox capacity while promoting the rapid separation and migration of photogenerated electron-hole pairs (e−/h+). Thus it was able to consume more electron donors to a certain extent, resulting in a higher initial photocurrent. In addition, BiVO4 with large spatial potential resistance was introduced for the first time to realize signal amplification. BiVO4 could not only compete with substrate materials for electron donors, but also effectively prevent electron donors from contacting the substrate, further reducing the photocurrent signal. Under optimized conditions, the sensor had a favorable detection range (0.0001–100 ng/mL) to CEA and a low detection limit of 0.03 pg/mL. With high specificity, excellent stability, and remarkable reproducibility, this sensor provided a new perspective for constructing accurate and convenient PEC immunosensor for bioanalysis and early disease diagnosisdisease diagnosis.

Bipedal DNA walker- CRISPR/Cas12a coupling with sulfur doped boron nitride–carbon nitride composite biosensing for the detection of miRNA-21

A novel photoelectrochemical (PEC) biosensor based on 2D–2D heterojunction S-BN/CN and dual-orbit three-dimensional (3D) bipedal DNA walker-synergized CRISPR/Cas12a signal amplification was fabricated for sensitive detection of miRNA-21. First of all, S-BN/CN, which sulfur was doped into boron nitride (BN) to construct heterojunction of 2D S-BN and 2D g-C3N4, was used as photosensitive materials to provide initial photocurrent, and combined methylene blue (MB) labeled hairpin DNA (MB-HP) as a signal probe. Secondly, after identifying the target miRNA-21, the two swing arms were simultaneously activated on two 3D orbits, cleaving along the orbit to output massive short single strand DNA (O-DNA) under the action of Nt.BsmAl endonuclease. Then trigger the trans-cleavage of CRISPR/Cas12a and cut off the hairpin DNA labeled with MB to achieve signal-off. The result showed that the proposed PEC biosensor had a good sensitivity for the detection of miRNA-21. It was a good linearity in the range of 10 fM - 100 nM, and the limit of detection was 3.98 fM (S/N = 3). The proposed PEC biosensor achieved sensitive detection with high specificity and low limit of detection for miRNA-21, while the rational design could be extended to achieve the detection of other targets.

Integration of surficial oxygen vacancies and interfacial two-dimensional NiFe-layered double hydroxide nanosheets onto bismuth vanadate photoanode for boosted photoelectrochemical water splitting

Considering its outstanding cost-to-efficiency ratio, N-type bismuth vanadate (BiVO4) is an ideal photoanode for photoelectrochemical (PEC) water splitting. Nevertheless, the widespread application of BiVO4 is being hindered commercially by innate challenges such as its poor carrier mobility, short hole diffusion length, and sluggish oxidation chemistry. Herein, we report the unique integration of surficial oxygen vacancies (Ovac) in conjunction with two-dimensional (2D) nickel-iron (NiFe) layered double hydroxide (LDH) nanosheets onto pristine BiVO4 photoanode to tweak the charge transfer kinetics during water splitting. The introduction of oxygen vacancies efficiently modulates band energetics, amplifies light absorption, and augments the carrier density. Concurrently, the 2D NiFe-LDH nanosheets play a dual role by facilitating interfacial hole transfer, thereby reducing excessive defect states, and serving as a protective layer against photocorrosion, ultimately resulting in a notable improvement in solar-driven water oxidation efficiency. The results of PEC water-splitting experiments demonstrate that the BiVO4 photoanode enriched with surficial oxygen vacancies and NiFe-LDH (BiVO4:Ovac/NiFe-LDH) achieved a photocurrent density of 2.92 mA cm−2 with ∼3-fold enhancement compared with a pristine BiVO4 photoanode. The engineered BiVO4 system yielded an impressive photoconversion efficiency of 1.29 %, charge separation efficiency (ηsep) > 40 %, and charge transport efficiency (ηtrans) > 35 %, clearly evidencing a boost in the charge dynamics of pristine BiVO4. Furthermore, during long-term stability testing, BiVO4:Ovac/NiFe-LDH retained 91 % of its initial photocurrent density for ∼20 h without any significant deterioration. This work sheds light on the role of integrating surface and interface engineering tactics for enhancing photo-induced charge transport in BiVO4, thereby providing efficient and stable PEC water splitting.

A novel Pt modified AlGaN/Si double-junction nanostructure for stable and self-powered solar blind photoelectrochemical photodetection

Simultaneously searching for self-powered, efficient, stable photoelectrode is the key to realizing the next-generation energy-efficient and sustainable integrated solar blind photoelectrochemical (PEC) photodetector. In this work, a Pt modified AlGaN/Si double-junction nanostructure with an n++ AlGaN/p++ AlGaN tunnel junction (TJ) and a AlGaN/Si junction is reported to achieve stable and self-powered solar blind photodetection. PEC tests demonstrate that the photocurrent density of the Pt modified AlGaN with n++ AlGaN/p++ AlGaN TJ photoelectrode can reach up to −56.1 μA/cm2 under 255 nm light irradiation with 1.1 mW/cm2 at 0 V bias versus a Pt counter electrode in a three-electrode configuration. Time-steady photoluminescence and XRD spectra are carried out and confirm the inherent optical and physical properties of this nanostructure. In addition, the multicycle and long-term stability measurement shows an excellent switching behavior even after being placed in the air for one month with a photocurrent density of −44.9 μA/cm2 (80% of its initial photocurrent). Furthermore, the PEC performance of the Pt modified AlGaN with n++ AlGaN/p++ AlGaN tunnel junction photoelectrode is evaluated in different light wavelengths, light intensities, bias potential and H2SO4 concentrations. These results demonstrate that the as-prepared photoelectrode has a great potential application in stable self-powered solar blind photodetector.

Organic-inorganic cascade-sensitized nanoarchitectonics for photoelectrochemical detection of β2-MG protein

Herein, a novel photoelectrochemical (PEC) immunoassay based on organic-inorganic BiVO4/rGO/FeOOH/C dot as cascade-sensitized photoactive material was fabricated for the ultrasensitive detection of β2-MG protein. Specifically, the composite BiVO4/rGO/FeOOH/C dot integrated the merits of high light absorption efficiency of organic material with fast electric carrier mobility of inorganic material. Additionally, the composite possessed a narrow energy level gradient, result in that the utilization of light energy improved greatly. More importantly, the composite with well-matched energy level would mediate multi-electron transport, thereby effectively promoting electron transfer and improving charge separation with an excellent photocurrent. Thereafter, through a typical sandwiched immunoreaction, quencher SiO2-labeled antibody that related to target was captured on electrode to decrease the initial photocurrent signal. The results showed that the proposed immunosensor exhibited high sensitivity and excellent stability in the linear range from 0.1 pg/mL to 1 μg/mL with a detection limit of 0.0383 pg/mL. This PEC biosensor offers a well-matched organic-inorganic cascade-sensitized strategy, providing novel insights to explore the high-performance photoactive material for application in early diagnosis of diseases.

Enhancing the photoelectrochemical activity and stability of plate-like WO3 photoanode in neutral electrolyte solution using optimum loading of BiVO4 layer and NiFe–LDH electrodeposition

Tungsten trioxide (WO3) is an attractive candidate that can be used as a photoanode in the photoelectrochemical (PEC) water splitting device. However, WO3 photoanode is known for its high thermodynamic and chemical stability only in strong acidic (low pH) electrolyte solution and its relatively wide bandgap energy (2.8 eV) leads to insufficient absorption of visible light. The current study explored a WO3/BiVO4 heterojunction photoanode, consisting of plate-like WO3 covered with a uniform and highly porous BiVO4 thin layer, with electrodeposition of NiFe–LDH as a co-catalyst for oxygen evolution reaction. This top layer of BiVO4 nanostructure not only exhibited an enhancement in absorption of visible light but also protected the underneath plate-like WO3 from being attacked by the neutral environment of electrolyte solution (pH=∼7), resulting in significant improvement in its stability. The electrodeposition of NiFe–LDH using an acidic aqueous electrolyte solution (pH=3.7) was employed to overcome the sluggish kinetics of water oxidation on the surface of BiVO4. To overcome the weakness of the chemical dissolution of BiVO4 nanostructure in strong acidic solution, the electrodeposition time was carefully optimized for 50 s, leading to a uniform distribution of co-catalyst on the surface of WO3/BiVO4 heterostructure without the dissolving of BiVO4 in the acidic media. The WO3/BVO5/NiFe50 photoanode with the highest PEC performance (photocurrent density of around 1.78 mA/cm2 at 1.23 V vs. RHE) could maintain around 75% of its initial photocurrent after 24 h.

Constructing DNAzyme-driven three-dimensional DNA nanomachine-mediated paper-based photoelectrochemical device for ultrasensitive detection of miR-486-5p

As a unique class of dynamic nanostructures, biomimetic DNA walking machines that exhibit geometrical complexity and nanometre precision have gained great success in photoelectrochemical (PEC) bioanalysis. Despite certain achievements, the slow reaction kinetics and low processivity severely restrict the amplification efficiency of the DNA walker-mediated biosensors. Herein, by taking advantage of efficient DNA rolling machines, a three-dimensional (3D) DNA nanomachine-mediated paper-based PEC device for speedy ultrasensitive detection of miR-486–5p was successfully constructed. To achieve it, a novel In2S3/SnS2 sensitized heterojunction was firstly in-situ grown on the Au-modified paper fibers and implemented as the photoanode with effective separation of photogenerated carriers to achieve an enhanced initial photocurrent. Subsequently, the copper hexacyanoferrate(II)-modified CuO nanosphere was introduced as a multifunctional signal regulator via the competitive capture of electron donors and photon energy with the photoelectric layer for efficiently quenching the PEC signal. With the introduction of targets, the DNAzyme-driven DNA nanomachine with editable motion modes was gradually activated and it could continuously cleave the tracks DNA labeled quenching probes, finally achieving the recovery of PEC signal. As a proof of concept, the elaborated paper-based PEC device presented a wide linear range from 0.1 fM to 100 pM and a detection limit of 35 aM for miR-486–5p bioassay. This work provides an innovative insight to the exploitation of DNA nanobiotechnology and nucleic acid signal amplification strategy.