Intervening Bismuth Tungstate with DNA Chain Assemblies: A Perception toward Feedstock Conversion via Photoelectrocatalytic Water Splitting

Sonochemical regulation of oxygen vacancies for Bi2WO6 nanosheet-based photoanodes to promote photoelectrochemical performance

Integration of oxygen vacancies (Vo) into nanostructured semiconductor-based photocatalysts has been recognized as a promising strategy for enhancing the performance of photoelectrochemical (PEC) water splitting. However, precisely controlling the Vo concentration in photocatalysts via an effective and tunable approach remains challenging. Herein, a series of optimized bismuth tungstate (Bi2WO6) nanosheet-based photoanodes with varying concentrations of Vo were prepared by a sonochemical method with in situ cavitation detection, which enables accurate manipulation of the acoustic cavitation intensity applied to the surface of Bi2WO6 photoanodes in alkaline solution. Based on the analysis of the Vo concentration and sound field characteristics, the mechanism of sonochemical regulation of Vo in Bi2WO6 nanosheets was interpreted. Specifically, the increase in Vo concentration can be attributed to the enhancement of Bi-O bond dissociation. This enhancement is influenced not only by the intensified impact of shear force and the generation of active radicals by transient cavitation, but also by the accelerated diffusion of the reactant, a result of stable cavitation. By optimizing the transient and stable cavitation intensity, a Vo-rich Bi2WO6 photoanode was obtained without altering the microstructure of Bi2WO6 nanosheets. The presence of high concentration Vo facilitates the interfacial chemical reactivity and the transmission of photogenerated carriers, leading to the drastic promotion of the PEC water splitting performance. The transient photocurrent density of the Vo-rich Bi2WO6 photoanode reaches 69.2 μA cm-2 (1.23 V vs. RHE), 7.86 times that of the untreated Bi2WO6 photoanode. Additionally, the charge injection efficiency increases to 35.4%. This work provides a controllable and effective method for defect engineering of nanostructured semiconductor-based electrodes.

Recent Development Strategies for Bismuth-Driven Materials in Sustainable Energy Systems and Environmental Restoration

Bismuth(Bi)-based materials have gained considerable attention in recent decades for use in a diverse range of sustainable energy and environmental applications due to their low toxicity and eco-friendliness. Bi materials are widely employed in electrochemical energy storage and conversion devices, exhibiting excellent catalytic and non-catalytic performance, as well as CO₂ /N₂ reduction and water treatment systems. A variety of Bi materials, including its oxides, chalcogenides, oxyhalides, bismuthates, and other composites, have been developed for understanding their physicochemical properties. In this review, a comprehensive overview of the properties of individual Bi material systems and their use in a range of applications is provided. This review highlights the implementation of novel strategies to modify Bi materials based on morphological and facet control, doping/defect inclusion, and composite/heterojunction formation. The factors affecting the development of different classes of Bi materials and how their control differs between individual Bi compounds are also described. In particular, the development process for these material systems, their mass production, and related challenges are considered. Thus, the key components in Bi compounds are compared in terms of their properties, design, and applications. Finally, the future potential and challenges associated with Bi complexes are presented as a pathway for new innovations.

Catalytic and SERS activities of WO3-based nanowires: the effect of oxygen vacancies, silver nanoparticle doping, and the type of organic dye

Oxygen vacancies in tungsten trioxide (WO₃) nanostructures (WO_3-x) dominate the major characteristics of the material and determine their activity in various applications including photocatalysis and surface-enhanced Raman spectroscopy (SERS). Despite some studies performed in the last decade, the photocatalytic activity toward different pollutants and SERS activity toward different Raman reporter molecules are still unclear and may provide valuable insights into this research field. Therefore, in this study, we propose WO_3-x nanowires (NWs) both as ideal photocatalysts for the degradation of organic pollutants such as crystal violet (CV), methylene blue (MB), malachite green (MG), and rhodamine 6G (R6G) and a SERS platform for the detection of these molecules. In the first step, WO_3-x NWs were fabricated through the solvothermal method. Afterward, the oxygen vacancy content of WO_3-x NWs was manipulated by the addition of silver ions or H₂O₂. Although H₂O₂ led to a remarkable decrease in oxygen vacancies (WO₃), the addition of silver ions led to the formation of Ag nanostructures on WO_3-x NWs (WO_3-x@Ag). Interestingly, the combination of WO_3-x and WO_3-x@Ag nanosystems with all dye molecules resulted in the formation of H-aggregates due to the strong electrostatic interaction between the nanostructure and dye molecules and then its photocatalytic degradation, while regular degradation of dyes was observed for WO₃. In SERS activity tests, each NP system exhibited different activities depending on various parameters including the chemical nature of the nanosystem, the degree of oxygen vacancy, the interaction of the Raman reporter molecule with the surface of the NP, and the resultant formation of H-aggregates or photocatalytic degradation. The combination of MB with WO_3-x, WO_3-x@Ag, and WO₃ created enhancement factors such as 1.6 × 10³, 5.4 × 10³, and 6.2 × 10³, respectively. This report showed that the parameters mentioned here must be considered in detail to evaluate the photocatalytic and SERS activity of the WO₃-based nanosystem.

Genomic DNA-mediated formation of a porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape bifunctional electrocatalyst for water splitting reactions

Among the accessible techniques, the production of hydrogen by electrocatalytic water oxidation is the most established process, which comprises oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Here, we synthesized a genomic DNA-guided porous Cu2(OH)PO4/Co3(PO4)2·8H2O rolling pin shape composite structure in one pot. The nucleation and development of the porous rolling pin shape Cu2(OH)PO4/Co3(PO4)2·8H2O composite was controlled and stabilized by the DNA biomolecules. This porous rolling pin shape composite was explored towards electrocatalytic water oxidation for both OER and HER as a bi-functional catalyst. The as-prepared catalyst exhibited a very high OER and HER activity compared to its various counterparts in the absence of an external binder (such as Nafion). The synergistic effects between Cu and Co metals together with the porous structure of the composite greatly helped in enhancing the catalytic activity. These outcomes undoubtedly demonstrated the beneficial utilization of the genomic DNA-stabilised porous electrocatalyst for OER and HER, which has never been observed.

DNA-based low resistance palladium nano-spheres for effective hydrogen evolution reaction

Highly stable and less resistance Pd/DNA NSs are designed for HER in acidic medium and require a low overpotential (η10) of 79 mV. DNA plays multiple roles such as stabilizer, structure-directing agent and binder in the fabrication of electrodes.