Direct Z-scheme-based novel cobalt nickel tungstate/graphitic carbon nitride composite: Enhanced photocatalytic degradation of organic pollutants and oxidation of benzyl alcohol

An integrated wearable microfluidic biosensor for simultaneous detection of multiple biomarkers in sweat

Simultaneous detection of biomarkers in sweat is crucial for comprehensive health assessment and personalized monitoring. However, the low sweat secretion rate and low metabolite concentrations present challenges for developing non-invasive wearable sensors. This study aims to develop a flexible wearable biosensor for simultaneous detection of low-concentration biomarkers in sweat, enabling comprehensive health assessment. This study synthesized an innovative bimetallic tungstate Ag@Ag2WO4 and evaluated its performance for detecting uric acid (UA, 10-1000 μM), dopamine (DA, 3-500 μM), and tyrosine (Tyr, 5-1000 μM). The detection limits (LODs) for DA, UA, and Tyr sensors were 3.10 μM, 8.47 μM, and 4.17 μM, respectively, with relative standard deviations (RSDs) of 4.76 %, 2.66 %, and 3.51 %, respectively. Additionally, this study designed a hydrophilic microfluidic collection system inspired by bamboo leaf structures to enhance sweat collection efficiency. Validation studies demonstrated that the wearable biosensor effectively detects UA and TA in the sweat of volunteers. We believe this research could contribute to advancing personalized healthcare by improving the convenience and effectiveness of health monitoring technologies.

Enhanced Fenton-like process over Z-scheme MoO3 surface decorated with Fe2O3 under visible light

Photocatalysts consisting of Z-scheme heterojunctions are commonly used in wastewater treatment due to their exceptional reactivity in photocatalysis and highly efficient visible-light utilization. In this work, Fe2O3-decorated MoO3 rods were synthesized through a two-step method and their photodegradation of methylene blue (MB) was evaluated. The Fe2O3/MoO3 rods were characterized by XRD, SEM, micro-Raman, XPS, UV-Vis DRS, and PL to investigate their structural, morphological, and optical properties. The results indicate that the photodegradation efficiency of Fe2O3/MoO3 improved through a reduction in the gap energy and persistence of a 1D hexagonal prism structure. The degradation rate of MB was enhanced from 31.7 to 91.5% after irradiation for 180 min owing to electron-hole separation and Fenton-like process. Formation of the OH radical is a key factor in the photodegradation reaction and with the addition of H2O2 the efficiency can further improve via a Fenton-like mechanism. Furthermore, the Z-scheme mechanism concurrently delineated. The Fe2O3/MoO3 rod composites were also found to retain high photocatalytic efficiency after being reused five times, which may be useful for future applications.

Photocatalytic degradation of acid blue 74 by Co: WO3 nanoparticles: Kinetics and response surface methodology studies

Energy-efficient sol-gel synthesis was achieved through the microwave assisted self-combustion route to produce hexagonal Tungsten oxide semiconductor (WO3). The photocatalytic activity was enhanced by doping Cobalt (Co) into the crystalline structure of the nanoparticle, which were subsequently sintered at 400 °C for an hour. The structural and morphological properties of the Co-doped WO3 were revealed using X-ray diffraction (XRD) characterization. The nanoparticles exhibited an amorphous structure before annealing, due to the short heating time during combustion synthesis. Sintering the nanoparticle transformed the nanoparticle from a monoclinic phase to orthorhombic phase structure. Additional analysis techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum analysis (EDS). To assess the photocatalytic performance of these particles, Acid Blue 74 (AB 74) was employed in photodegradation experiments under UV light irradiation within a semi-continuous reactor. The photodegradation of dye molecules was evaluated utilizing a UV-Vis spectrophotometer, and the mineralization efficiency of the dye was determined through total organic carbon analysis (TOC). The results indicated that the dimension of the synthesized nano catalyst fell within the range of 70-120 nm, and it exhibited the ability to completely degrade a solution with an initial dye concentration of 20 ppm within 60 min. Various parameters affecting the photocatalytic reaction, including the photocatalyst dosage, initial dye concentration, pH and temperature of the dye solution were also investigated. The experiments were designed using Response surface methodology (RSM), through which a mathematical model for the dye removal process was developed.

Construction of a stable S-scheme NiSnO3/g-C3N4 heterojunction on activated carbon fibre for the degradation of glyphosate in water under flow condition

Creating light-harvesting heterojunctions as a photocatalyst is critical for efficiently treating organics-laden wastewater. Yet the materials stabilization and limited reusability hinder their practical applications. In this study, an S-scheme heterojunction in the Sn-based perovskite and g-C3N4 (gCN) composite, supported on an activated carbon fiber (ACF) substrate, is developed for glyphosate (GLP) degradation under water under flow conditions. The reusable NiSnO3-gCN/ACF photocatalyst was synthesized using a simple wet impregnation and calcination method. The supported photocatalyst achieved 99% GLP-removal at 4 mL/min water flowrate and 1.25 g/m2 of photocatalyst loading in ACF. The photocatalyst showed a stable structure and repeat photocatalytic performance across 5 cycles despite prolonged visible light exposure under flow conditions. The materials stability is attributed to the effective dispersion of NiSnO3-gC3N4 in ACF, preventing the photocatalyst from elution in water flow. Radical trapping experiment revealed the superoxide and hydroxyl radicals as the primary reactive species in the GLP-degradation pathway. A plausible S-scheme mechanism was proposed for heterojunction formation, based on the high resolution deconvoluted spectra of X-ray photoelectron spectroscopy and the radical trapping experimental results. The inexpensive Sn-based perovskite synthesized in this study is indicated as an alternative to Ti-based perovskites for wastewater remediation application.

Covalently anchoring silver nanoclusters Ag44 on modified UiO-66-NH2 with Bi2S3 nanorods and MoS2 nanoparticles for exceptional solar wastewater treatment activity

For the first time, covalently anchoring size selected silver nanoclusters [Ag44(MNBA)30] on the Bi2S3@UiO-66-NH2 and MoS2@UiO-66-NH2 heterojunctions were constructed as novel photocatalysts for photodegradation of methylene blue (MB) dye. The anchoring of Ag44 on MoS2@UiO-66-NH2 and Bi2S3@UiO-66-NH2 heterojunctions extended the light absorption of UiO-66-NH2 to the visible region and improved the transfer and separation of photogenerated charge carriers through the heterojunctions with a unique band gap structure. The UV-Vis-NIR diffuse reflectance spectroscopic analysis confirmed that the optical absorption properties of the UiO-66-NH2 were shifted from the UV region at 379 nm to the visible region at ~ 705 nm after its doping with Bi2S3 nanorods and Ag44 nanoclusters (Bi2S3@UiO-66-NH-S-Ag44). The prepared Bi2S3@UiO-66-NH-S-Ag44 and MoS2@UiO-66-NH-S-Ag44 photocatalysts exhibited exceptional photocatalytic activity for visible light degradation of MB dye. The photocatalysts exhibited complete decolorization of the MB solution (50 ppm) within 90 and 120 min stirring under visible light irradiation, respectively. The supper photocatalytic performance and recycling efficiency of the prepared photocatalysts attributed to the covalent anchoring of the ultra-small silver clusters (Ag44) on the heterojunctions surface. The X-ray photoelectron spectroscopic analysis confirmed the charge of the silver clusters is zero. The disappearance of the N-H bending vibration peak of primary amines in the FTIR analysis of Bi2S3@UiO-66-NH-S-Ag44 confirmed the covalent anchoring of the protected silver nanoclusters on the UiO-66-NH2 surface via the condensation reaction. The Bi2S3@UiO-66-NH-S-Ag44 catalyst exhibited excellent recyclability efficiency more than five cycles without significant loss in activity, indicating their good potential for industrial applications. The texture properties, crystallinity, phase composition, particle size, and structural morphology of the prepared photocatalysts were investigated using adsorption-desorption N2 isotherms, X-ray diffraction (XRD), HR-TEM, and FE-SEM, respectively.

Enhanced photodegradation of organic contaminants using V-ZnSQDs@TiO2 photocatalyst in an aqueous medium

Vanadium-doped zinc sulfide quantum dots complexed with TiO₂ have been designed using the sol-gel technique and characterized using analytical techniques, such as X-ray diffraction analysis (XRD), UV-Vis diffuse reflectance spectra (DRS), Fourier transforms Infra Red (FTIR), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscopy (TEM). The X-ray diffraction analysis of the composite material showed sharp peaks corresponding to both TiO₂ and ZnS_QDs. The FTIR analysis exhibits a strong and broad absorption at 807 cm^-1 indicating the assimilation of vanadium metal in the ZnS_QDs lattice. The DRS spectra showed a bathochromic shift of 25 nm in the synthesized V-ZnS_QDs@TiO₂ composite compared with the pure sample. The photocatalytic performance of the synthesized composite was tested by studying the degradation of two different chromophoric organic dyes, rhodamine B (RhB), methylene blue (MB) and a drug derivative paracetamol (PCM) in aqueous suspension under UV-light illumination. Among the synthesized materials, the composite (V-ZnS_QDs@TiO₂) was established to be more active than the pure ZnS_QDs, TiO₂, and V-ZnS_QDs for the degradation of compounds under investigation. The activity of the synthesized catalyst was also tested for the mineralization of all compounds by measuring the depletion in total organic carbon (TOC) at different irradiation times. The results showed that the catalyst degrades the compounds and mineralizes them efficiently. The primary reactive species involved in the photodegradation reaction were determined by quenching studies, terephthalic acid, and NBT probe methods. A probable mechanistic pathway for the decomposition of compounds has been proposed.

Photocatalytic oxidation of glyphosate and reduction of Cr(VI) in water over ACF-supported CoNiWO4-gCN composite under batch and flow conditions

Photocatalytic treatment of wastewater using nanomaterials is an efficient energy saving technology. Yet the practical application of the technology is limited because of difficulty in developing the stable, supported photocatalytic nanoparticles that can be used under continuous flow conditions. Here, we report an efficient removal of glyphosate (GLP) and Cr(VI) from water under batch as well as continuous flow conditions using the activated carbon fiber (ACF)-supported nanocomposite of CoNiWO4 (CNW) and g-C3N4 (gCN), as a photocatalyst. CNW-gCN/ACF is synthesized using a one-step strategy, and spectroscopic characterization techniques are used to corroborate the formation of the Z-scheme-based CNW-gCN heterojunction in the ACF substrate. Efficacy of the photocatalyst is assessed in visible light irradiation. The batch activity data of the individual pollutant show the complete oxidation of GLP at 30 ppm and reduction of Cr(VI) at 200 ppm concentration levels in 60 and 150 min, respectively at 1 g/L dose of CNW-gCN/ACF. Photocatalytic efficiency of CNW-gCN/ACF in the simultaneous removal of both pollutants from co-contaminated feed is found to be greater than that in single-feed system under identical experimental conditions. Tested under flow conditions, CNW-gCN/ACF shows approximately the same rates of oxidation and reduction as prevalent under batch conditions, indicating the efficient immobilization of the nanocatalyst particles in ACF, which not only prevents elution of the catalyst but also improves its reusability. The toxicity data indicate the treated water samples to be non-toxic. The current study provides an efficient method for developing supported nanomaterial photocatalysts for treating flowing co-contaminated wastewater.