Simulated Sunlight Illumination Research Articles

Synthesis of strongly interactive FeWO4/BiOCl heterostructures for efficient photoreduction of CO2 and piezo-photodegradation of bisphenol A

Development of multi-functional photocatalysts for CO2 reduction and pollutant elimination is practically significant for solving the environmental problems and energy shortages. In this study, we have immobilized FeWO4 (FWO) nanoparticles on the surface of (001)-facet-exposed BiOCl (BOC) nanosheets through their strong electrostatic interaction to form FWO/BOC heterojunctions. Experimental and theoretical studies corroborate that the FWO/BOC heterojunctions exhibit high-efficiency Z-scheme transfer and separation of photocarriers, and possess excellent photocatalysis for CO2 reduction and bisphenol A (BPA) degradation. Under simulated-sunlight irradiation, the 9 %FWO/BOC heterojunction exhibits a photoreduction performance with CH4/CO yield rates of 4.25/9.41 μmol g−1 h−1 (5 h reaction), which are 3.86/5.26 times higher than those for bare BOC; whereas its photodegradation performance (η(60 min) = 66.8 %, kapp = 0.01755 min−1) is enhanced by 4.3 and 2.7 times compared with that of bare FWO and BOC, respectively. Furthermore, when ultrasonic vibration is simultaneously employed during the simulated-sunlight illumination, the ultrasonic-induced piezoelectric polarization field in BOC nanosheets accelerates the bulk photocarrier separation, resulting in a further improvement in the BPA degradation, and the calculated SF = 1.79 quantifies the degree of enhancement achieved by piezo-photocatalysis collaboration. The introduction of a moderate amount of H2O2 or peroxymonosulfate (PMS) in the reaction solution plays a significant role in promoting the BPA degradation due to the generation of additional •OH and •SO4− reactive species. The mechanisms for photocatalytic CO2 reduction and piezo-photodegradation of BPA catalysis were deeply studied by combining experiments and theory.

Textile dyes removing from the wastewater by green synthesized Cu-doped ZnO photocatalysts under the simulated sunlight illumination

Herein, Cu-doped ZnO photocatalysts were prepared via green synthesis method with utilization of Cannabis Sativa leaves. The catalytic activity was evaluated through the degradation of methylene blue (MB) and rhodamine B (RhB) under the simulated sunlight illumination. XRD, FESEM, EDAX, FTIR, BET-BJH and DRS were used for characterizations of Cu-doped ZnO. The results showed that, 3 wt % Cu-doped ZnO (CuZn3) displayed the excellent characterizations such as uniform dispersion, lower energy bandgap, smaller average particle size and greater surface area. For the photocatalysts with higher Cu loading (more than 3 wt %), non-uniform dispersion with larger particles, lower specific surface area and higher energy bandgap were found. The average particle size and energy bandgap for CuZn3 were 37.7 nm and 2.9 eV, respectively. Due to the superior properties, CuZn3 presented the highest amount of dyes degradations. After 180 min test, MB and RhB degradations by CuZn3 were 92.1 and 94.2 %, respectively. Moreover, it was found that optimum amount of CuZn3 was 100 ppm. Furthermore, applying of various scavengers revealed that hydroxyl radicals, superoxide radicals, and photo-generated electrons were the primary forms of radicals involved in dyes degradation using Cu-doped ZnO photocatalysts.

Bulk photovoltaic effect in Cu-doped LiNbO3 single crystals with controlled oxidation state

We investigate the bulk photovoltaic (PV) effect of Cu-doped LiNbO3 single crystals with various oxidation states of Cu. The Cu-doped samples exhibit the PV response under below-bandgap excitation, and the onset of photocurrent shifts depending on partial oxygen pressures (pO2) during the annealing treatment. Open-circuit voltages (V oc) under simulated sunlight (AM 1.5 G) illumination are changed by pO2, and crystals annealed at pO2 = 1.0 × 10−10 atm exhibit the highest V oc of 1700 V. Moreover, density functional theory (DFT) calculations for Cu-doped LiNbO3 cells with Cu2+ on the Li site and the Nb site indicate that half-filled gap states derived from 3d orbitals of Cu are formed within the bandgap. Based on Glass coefficients obtained by the analyses of polarization angle-dependent photocurrent densities and the DFT calculations, we consider that Cu2+ on the Li site is the major active site for the generation and separation of electron–hole pairs under visible light at hν = 2.4 eV.

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.

A self-standing dual-electric field synergistic Janus nanofibre piezoelectric photocatalyst with degradation of antibiotics: Performances, DFT calculation and mechanism unveiling

A self-standing dual-electric field synergistic [TiO2/polyvinylidene fluoride (PVDF)]//[g-C3N4 tube/PVDF] Janus nanofibres (named as [TP]//[CTP]JNs) S-scheme heterostructure piezoelectric photocatalyst is designed and constructed via conjugative electrospinning. Dual-fields of built-in electric fields supplied by S-scheme heterostructure and piezoelectric field formed by PVDF jointly boost separation and transfer of photo-induced charges. As a case study, piezoelectric photocatalytic efficiency of [TP]//[CTP]JNs for tetracycline hydrochloride (TCH) under ultrasonic united with simulated sunlight illumination is 93.35% (40 min), which is 1.39 times of the photocatalytic efficiency (light illumination only) and 5.32 times of piezoelectric catalytic efficiency (applying ultrasonic only), proving the advantages of the synergistic effect of piezoelectric catalysis and photocatalysis on contaminant degradation. The dynamic behaviors of photocatalysis and photo-generated charges are deeply revealed through fs-TA and TRPL decay spectra, and the degradation pathways of antibiotics are reasonably speculated by combining LCMS spectra with Fukui index. By the degradation ability, COMSOL simulation and DFT calculation, the structural advantage of Janus nanofibers is fully verified, and S-scheme charge transfer mechanism is confirmed by combining a series of sound ample experiments with theoretical calculations. Additionally, the construction mechanism of Janus nanofibers is proposed, and corresponding construction technique is established.

Enhanced photocatalytic degradation of oxytetracycline by Z-scheme heterostructure ZIF-8/Bi4O5Br2

Semiconductor photocatalysis technology has a wide range of application in the treatment of environmental pollution. In this study, the Z-scheme heterojunction photocatalyst ZIF-8/Bi4O5Br2 was synthesized by hydrothermal method. The morphology, structure, mechanism and photocatalytic performance of the materials were studied. Under simulated sunlight illumination for 60 minutes, the degradation efficiency of oxytetracycline (15 mg·L−1) reached 94.2 %. In light of density functional theory calculation and liquid chromatography-mass spectrometry, the attack sites and degradation pathways of OTC were determined. The consequence of free radical capture test and electron paramagnetic resonance detection showed that ·O2-, ·OH and h+ were the primary active substances. Based on the analysis above, the charge transfer principle of Z-scheme heterojunction was further elucidation. It inhibited the recombination of photo carriers and improved the photocatalytic performance. This work provides a hopeful measure for photocatalytic degradation of OTC by Z-scheme heterojunction composite.

The construction of Cs3MoxSbyBr9/BiVO4 S-scheme heterojunction photocatalyst for efficient photocatalytic N2 fixation

Synergistic nitrogen (N2) reduction with water (H2O) oxidation is meaningful but challenging owing to the inertness of the N2 molecule and the sluggish kinetics of H2O oxidation. Herein, a simutaneous-promotion strategy of redox capacities is presented for constructing a lead-free Cs3Sb2Br9-based S-scheme heterojunction, by decorating Mo-functionalized Cs3Sb2Br9 nanocrystals (Cs3MoxSbyBr9) on BiVO4 nanosheet through an in-situ plane-to-point growth manner. The Mo-functionalization for Cs3Sb2Br9 enables the regulation of the d-band center position, greatly improving surface reaction kinetics for N2 reduction. Furthermore, the construction of the S-scheme heterojunction enhances the driving force for H2O oxidation and spatial charge separation of photocatalysts. As anticipated, the resultant Cs3MoxSbyBr9/BiVO4 exhibits an excellent photocatalytic N2 reduction activity under ambient atmosphere, achieving ammonia (NH3) production at a rate of 300 ± 5 μmol g−1 h−1 under simulated sunlight illumination (100 mW cm−2), which is nearly 20-fold higher than that of pristine Cs3Sb2Br9.

Construction of ternary AuPt/Bi2WO6/ZnIn2S4 heterostructures for photocatalytic degradation of tetrabromobisphenol A

How to fascinate the separation of the photogenerated electrons and holes is very crucial to enhance the photocatalysis of semiconductors. Herein we have prepared AuPt/BWO/ZIS heterostructured photocatalysts by decorating Bi2WO6 (BWO) nanoflakes and AuPt nanoparticles on the surface of ZnIn2S4 (ZIS) hierarchical microspheres. The photocatalysis of the samples was evaluated by degrading tetrabromobisphenol A under simulated-sunlight illumination. It is demonstrated that the ternary AuPt/BWO/ZIS photocatalysts exhibit obviously enhanced photocatalysis in comparison with bare BWO and ZIS as well as the binary BWO/ZIS photocatalysts. The highest photocatalysis is observed for 3%AuPt/40%BWO/ZIS, whose photodegradation performance is improved by 3.9 and 6.2 times over that of single BWO and ZIS, respectively. This phenomenon can be explained due to several reasons: the photocarriers are efficiently separated due to the charge transfer across the BWO/ZIS and AuPt/ZIS interfaces, surface plasmon resonance of AuPt nanoparticles stimulate ZIS to produce additional electron/hole pairs, and the SPR-induced electrons in the AuPt nanoparticles could also take part in the photocatalysis. Additionally, the effect of various factors on the tetrabromobisphenol A degradation was investigated; the degradation pathways of tetrabromobisphenol A and the potential toxicity of the degradation by-products were evaluated.

Highly efficient photocatalytic decarboxylation of fatty acids to alkanes enabled by photothermal conversion effect

Heating is the most straightforward means to achieve rapid, high-flux production of thermal catalytic reactions, but photocatalysis rarely uses it mainly because their intrinsic driving force depends on the photogenerated carriers separation , which has always been treated as little dependent of temperature and sometimes even with negative dependence. Here we report a temperature-dependent strategy of in-situ thermal-assisted photocatalytic decarboxylation of bioderived long-chain fatty acids into Cn–1n-alkanes over Sb2S3 photocatalyst. Under concentrated simulated sunlight illumination without external heating, this reaction system is readily self-heated to boiling (254 °C) of n-tetradecane solvent only by the photothermal conversion effect of Sb2S3. The heat from the incident light enables the standing C-chain at low temperature down onto the surface of Sb2S3 resulted in the CCOO− bonds with more strain, which makes it easier for light-induced hvb+/ecb− to approach and react with the energy-storing CCOO− bonds, thereby resulting in an increase in n-alkane single output concentrations exceeding five orders of magnitude. Our study demonstrated the vast majority of incident light energy could be harnessed in a heat form to enhance the efficiency of photocatalytic decarboxylation.

Au/Ti3C2/g-C3N4 Ternary Composites Boost H2 Evolution Efficiently with Remarkable Long-Term Stability by Synergistic Strategies.

The use of novel two-dimensional MXene materials and conventional g-C3N4 photocatalysts to fabricate the composites for hydrogen evolution reaction (HER) has attracted much attention, for which there is plenty of room for the enhancement of hydrogen evolution rates particularly under visible light and photostability. Herein, g-C3N4 was modified by copolymerization of malonamide and melamine and used to fabricate the ternary composites of Au particles and Ti3C2 MXene, and based on the synergistic effect, the composites enhanced the hydrogen evolution rates by 2.1, 99.8, and ∞ times compared with the unmodified g-C3N4 under UV, simulated sunlight, and visible light illumination, respectively. Moreover, the composite exhibited a sustained hydrogen evolution capacity in the cycle test for up to 120 h. Theoretical calculations and experimental results indicated that the hot electrons of Au are injected into the modified g-C3N4 and transferred to Ti3C2 simultaneously along with the photogenerated electrons of the modified g-C3N4 and then further transferred to Au, forming a photogenerated electron transfer channel of Au and modified g-C3N4 → Ti3C2 → Au within the composite. Ti3C2 acts as a bridge for fast separation of photogenerated electrons and holes on Au and modified g-C3N4, playing a key role in the enhanced photocatalytic performance. In addition, the visible light absorption ability of Au also positively contributed to the enhancement of visible light photocatalytic performance by providing hot electrons. Therefore, the selection of suitable cocatalysts for the design of composites is a crucial research direction to improve the photocatalytic performance and photostability of photocatalysts.

Solvothermal synthesis of novel ternary BiOI–BiOBr–NiO nanophotocatalyst with improved solar light photocatalytic activity

A novel class of heterojunction BiOI–BiOBr–NiO has been synthesized through solvothermal-precipitation route. Novel as-prepared nanophotocatalysts are highly efficient under simulated sunlight illumination for (Acid Orange 7) AO7 degradation. Even though, NiO possess no photocatalytic efficiency, its combination with BiOBr–BiOI provides exceptional high photocatalytic performance due to more effective photo-generated electron–hole separation through the heterojunction semiconductor construction. XRD, FESEM, EDX, BET, FTIR and DRS analysis were applied to identify the physical, chemical and optical properties of the synthesized BiOI–BiOBr–NiO heterojunctions. The results showed remarkable increase of photoactivity of BiOI–BiOBr–NiO (6:3:1) in comparison with corresponding heterostructures. XRD confirms construction of BiOBr–BiOI over NiO nanoparticles. In addition, 3D image of synthesized samples affirms proper roughness and porosity. The effect of parameters including catalyst loading, pH and dye concentration has been examined. According to recycling tests and XRD of used sample, the novel heterojunction system considered to be photo table.

CQDs-interspersed floral CdS/NiAl-LDH heterojunction towards efficient photoreduction of CO2-to-CO

A series of hierarchical flower-like CdS/carbon quantum dots/NiAl-LDH (CCL) photocatalyst have been successfully prepared to achieve efficient conversion of CO2-to-CO via a simple yet effective hydrothermal method. In the CCL, interspersed-CQDs not only increase the number of reactive sites but also reduce inner electronic impedance with the assistance of light reflecting-scattering effect. This significantly improves electron migration efficiency and inhibits the recombination of photoinduced electron-holes pairs. Without any sacrificial agent or photosensitizer, the sample of CCL-1 exhibits the highest CO evolution rate of 7.04 μmol·g−1·h−1 in water under simulated sunlight illumination with a large specific surface area (129.15 m2 g−1) and an appropriate CQDs content of 15.2 wt%, which is 12.8- and 11.2-fold higher than those of pristine LDH, pure CdS, and many previously reported LDH-based counterparts. A type-Ⅱ interfacial charge transfer mechanism is proposed, where electrons migrate rapidly from CdS to LDH with highly-interspersed CQDs as unhindered electron conduction bridges. The present work outlines a simple and controllable LDH-based heterojunction, which give rise to superior photocatalytic activity for CO2 photoreduction.

Development of ternary Pt/BaTiO3/Bi2O3 heterostructured piezo-photocatalysts for antibiotic degradation

The efficient separation of surface and bulk photocarriers is very crucial for improving the photocatalytic activity of semiconductors. To achieve this goal, herein we have developed ternary Pt/BaTiO3/Bi2O3 (Pt/BTO/BO) heterostructured piezo-photocatalysts with high capacity for antibiotic degradation. The ternary heterostructures were constructed by anchoring BTO and Pt nanoparticles on the surface of BO microrods. Their piezo-photocatalytic performance and mechanism was elucidated through the degradation of ciprofloxacin (CIP). It is revealed that the ternary heterostructures exhibit obviously enhanced photocatalysis under illumination of simulated sunlight; typically the photocatalytic activity of the 2 %Pt/9%BTO/BO sample is improved by 8.2 and 2.4 times over that of single BTO and BO, respectively. This phenomenon originates from the improved separation of photocarriers by the BTO/BO and Pt/BO interface fields. More interestingly, when simulated-sunlight illumination was accompanied with ultrasonic vibration, the piezo-photocatalysis of 2 %Pt/9%BTO/BO shows a further improvement in the CIP degradation. The coupled piezo-photocatalysis shows a synergistic enhancement factor SF = 2.64. Efficient separation of bulk photocarriers, which is caused by ultrasonic-induced piezoelectric polarization field, is the main reason for the elevated piezo-photocatalysis. Additionally, the decomposition process of CIP and potential toxicity of substances generated during the CIP degradation process were elucidated.

Coupled piezo-pyro-photocatalysis of oxygen vacancies and Bi quantum dots co-modified BaTiO3 for highly efficient removal of ciprofloxacin

Understanding the synergistic promotion of photocarrier separation by multiple parameters is crucial to developing superior photocatalysts in environmental remediation. In this study, we have engineered BaTiO3 photocatalyst by creating oxygen vacancies (OVs) and decorating Bi quantum dots (QDs) on its surface, and then elucidated its piezo-pyro-photocatalysis and mechanism for ciprofloxacin (CIP) elimination. The optimal OVs-/Bi QDs-engineered sample (labeled as 7 %Bi@BTO-325 °C) exhibits a photodegradation activity, under simulated-sunlight irradiation, that is improved by 3.8 times over that of pristine BTO. This phenomenon can be explained due to the improved visible-light absorption and photocarrier separation by OVs and Bi QDs. Moreover, when the simulated-sunlight illumination (photocatalysis) was companied with ultrasonic irradiation (piezocatalysis) and cold-hot alternation (pyrocatalysis), the coupling of piezo-pyro-photocatalysis shows a further improvement in the CIP removal with a synergistic enhancement factor SF = 1.77. The enhanced piezo-pyro-photocatalysis is ascribed to the fact that the piezoelectric/pyroelectric polarization field facilitates the separation of photocarriers (particularly the bulk photocarriers). Experiment and theory were combined to deeply study the catalysis mechanism. Moreover, the influence of multiple parameters on the CIP elimination was investigated and analyzed by machine learning to establish the best prediction model.

BISMUTH OXYCHLORIDE NANOSHEETS MODIFIED WITH Au-Cu NANOPARTICLES FOR EFFICIENT PHOTOREDUCTION OF CO2 TO ETHANE

BiOCl nanosheets modified with AuCu nanoparticles were successfully designed and fabricated for water reduction of CO2. The AuxCuy/BiOCl composites exhibited enhanced visible light absorption ability due to a surface plasmon resonance (SPR) effect. The AuxCuy/BiOCl composites could convert carbon dioxide to ethane (C2H6), while only CO was obtained over pure BiOCl nanosheets. In this study, the rate of C2H6 production (12.2 μmol h-1 g-1) and selectivity of C2H6 (75.7%) were obtained over the Au1Cu1/BiOCl photocatalyst under simulated sunlight illumination. The AuCu nanoparticles played the dual role of electron traps and hot electron donors, facilitating efficient separation and migration of the carriers. The photocatalyst exhibited steady photocatalytic activity over the test duration of 9 h.

Synergistic effect of adsorption-photocatalytic reduction of Cr(VI) in wastewater with biochar/TiO2 composite under simulated sunlight illumination.

Photocatalysis, which is an alternative technology to conventional methods, utilizes solar energy as the driving force to address environmental concerns and has attracted widespread attention from chemists worldwide. In this study, a series of photocatalytic materials composed of agricultural waste and titanium dioxide (TiO2) nanomaterial was prepared for the synergistic adsorption-photocatalytic reduction of hexavalent chromium in wastewater under mild conditions. The results showed that the TiO2 nanomaterial exhibited a higher photogenerated carrier separation efficiency and performance for the adsorption-photocatalytic reduction of Cr(VI) after loading straw biochar (BC). When the loading amount of BC was 0.025 g (i.e., TBC-3), the removal efficiency of Cr(VI) was as high as 99.9% under sunlight irradiation for 25 min, which was 2.9 and 3.5 times higher than that of pure TiO2 and BC samples, respectively. Additionally, after four cycles of experiments, the removal efficiency of Cr(VI) by TBC-3 remained at about 93.0%, proving its good chemical ability in our reaction system. Its excellent adsorption-photocatalytic performance is mainly attributed to the synergistic effect of the strong adsorption of BC and the outstanding photocatalytic performance of TiO2. Finally, the possible mechanism for the synergistic adsorption-photocatalytic reduction on BC/TiO2 to remove the highly toxic Cr(VI) in wastewater was proposed.

Silicon-based heterojunction photoanodes modified with copper-bipyridine catalyst for enhanced solar-driven water splitting

In photoelectrochemical (PEC) water splitting, accelerating the carrier transfer from the semiconductor to the catalytic functional layer through the construction of nanostructure-heterojunction interface is an effective method to overcome the intrinsically slow kinetics of the photoanode phase interface. In this work, p-type NiO and n-type TiO2 layers were deposited on the surface of n-type Si electrodes, respectively, to construct p-n and n-n heterojunction photoanodes. Moreover, a copper-bipyridine molecular catalyst, namely Cu(dcbpy), was deposited on the heterojunction photoanodes to furtherly provide transfer path for the photogenerated holes in water splitting. Under the illumination of simulated sunlight, the Si/NiO/Cu(dcbpy) photoanode exhibits a high photocurrent density of 16.63 mA cm−2 at 2.2 VRHE, which is 277.2 times of n-Si and 1.92 times of Si/TiO2/Cu(dcbpy) at the same condition. This result indicates that p-n heterojunction accelerates the photogenerated holes transfer from Si to the electrocatalyst of Cu(dcbpy) to achieve a high water-splitting efficiency. This work provides an approach to designing efficient Si-based photoanodes through nanostructure-heterojunction interface engineering and molecular catalyst modification.

Coal Pitch Derived Yellow‐Emissive Carbon Dots and Their Application in Luminescent Solar Concentrators

AbstractUsing coal pitch as the carbon source to synthesize carbon dots (CDs), one of the most promising photoluminescence (PL) materials, can play an important role in the global demand for carbon neutralization. However, the reported CDs derived from coal pitch are mainly limited blue emission. Here, a new route to synthesize yellow‐emissive CDs from coal pitch is developed by extracting the lightweight aromatic compounds from coal pitch and solvothermally treating the extracts in dichloromethane in the presence of a small amount of nitric acid and sulfuric acid. Notably, the obtained CDs exhibit excitation independent yellow emission, large Stokes shift and good photostability. The application of the CDs for luminescent solar concentrators (LSCs) is evaluated. It is found that the CDs can be well dispersed in polymethyl methacrylate (PMMA) matrix and fabricated transparent LSCs. The synthesized LSC (4 × 4 × 0.2 cm3) with the optimal CDs concentration exhibits an optical conversion efficiency (ηopt) of 3.31% and power conversion efficiency (ηPCE) of 1.95% under simulated sun light illumination (100 mW cm−2). This research offers a new strategy to synthesize new kind of CDs with desired performance by exploiting the native chemistries of coal pitch.

Rational design of coaxial CdS@ZnO nanowire array for efficient photodegradation of organic pollutants

Herein, a novel coaxial CdS@ZnO nanowire array catalyst was synthesized by magnetron sputtering and hydrothermal method. The optimum photocatalytic composite was obtained by controlling the ratio of CdS and ZnO. Take methylene blue (MB) as the model, the CdS@ZnO nanowire array (CdS@ZnO-10) exhibited strong photocatalytic solid activity, and the highest adsorption and photodegradation rate of MB reached 90.38 % in 50 min and 99.13 % in 120 min under simulated sunlight illumination. The mechanism of the heterojunction interface affecting photocatalytic performance was studied. Therefore, the synthesis approach could offer new design and controllable construction of coaxial structure for organic dye pollutant degradation.

Synergistic integration of MoOx co-catalyst with oxygen vacancies-engineered on BiVO4 for enhancing the sensitivity of photoelectrochemical DNA biosensing

Photoelectrochemical (PEC) biosensors of deoxyribonucleic acid (DNA) hybridization with simultaneously high signal-to-noise ratio and low limit-of-detection remains greatly challenging owing to the rapid recombination of photogenerated carriers of photoelectrode. Herein, we report an efficient strategy to amplify the photocurrent signal by coupling the MoOx co-catalysts and surface oxygen vacancies (Ov) of BiVO4 as photoelectrode (MoOx/BiVO4-Ov). Using a simple in situ solution impregnation method, non-noble metal MoOx nanoparticles can be grown uniformly onto BiVO4, subsequently, abundant surface Ov of MoOx/BiVO4 is induced by N2-plasma treatment. The coupling of MoOx and surface Ov on BiVO4 can efficiently promote the separation of photogenerated carriers, as a result, the optimized MoOx/BiVO4-Ov shows an excellent photocurrent response of 300.52 μA/cm2 under simulated sunlight illumination, which is 59.6 and 5.4 times higher than that of pristine BiVO4 and MoOx/BiVO4, respectively. Furthermore, the PEC biosensor based on MoOx/BiVO4-Ov demonstrates an excellent sensitivity toward DNA hybridization (10 pM to 10 μM) with a calculated detection limit down to 0.0549 pM. Moreover, this PEC biosensor exhibits specific selectivity as well as high stability. The proposed amplification strategy by the synergistic effect of co-catalysts and defects is valuable for the construction of efficient sensors for the early diagnosis of multiple diseases.