Photocatalytic solar energy transformation is the most encouraging solution to alleviate the environmental crisis and energy scarcity. Bismuth oxyhalide (BiOX) is an emerging class of materials that exhibits photocatalytic properties, such as resilient response to light, which causes enhanced energy conversion (solar energy) owing to their exceptional layered structure and attractive band structure. The present review presents a summary of results from the recent developments on the tuning and design of BiOX-based materials to improve the energy conversion. In particular, the preparation and tuning approaches that have the potential to enhance the photocatalytic behavior of BiOX and some other techniques, such as elemental doping, are addressed, which prevent the rapid recombination of charges, and formation of oxygen vacancies, facilitating an improvement in the photocatalytic reaction. Various frameworks are also presented, displaying the significance of BiOX-based nanocomposites. Finally, the main challenges and opportunities associated with the future progress of BiOX-based materials are presented. This review will provide an extended understanding and offer a preferred direction for the innovative design of BiOX-based materials for environmental and especially energy-based applications.

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A review on bismuth oxyhalide based materials for photocatalysis

In this work, vertically grown rod type ZnO nanostructures have been synthesized on metallic nickel tube films fabricated through the cost-effective process of electroforming. The use of tubular metal substrates for the growth of ZnO nanorods has been found to be advantageous for the photocatalytic degradation of EtBr dye because of their high surface area-to-volume ratio. The nickel tubes with ZnO nanorods were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The developed system was utilized for the photocatalytic degradation of EtBr dye and its efficacy was revealed through the comprehensive mineralization of the dye within 150 min. The mechanism of the degradation process has been revealed through total organic carbon (TOC), chemical oxygen demand (COD) and high-performance liquid chromatography (HPLC) studies. A substantially lower amount of the photocatalyst has been used because of the homogeneously distributed growth of nanorods on the substrate. Density functional theory-based analysis has also been performed to study the photocatalytic degradation and adsorption properties of EtBr on ZnO nanorods. Using first principles DFT theory, geometry optimizations and vibrational analysis are performed which show a negative charge transfer from the substrate to the photocatalyst. For the first time this article reports the use of DFT analysis for investigating the adsorption of EtBr on ZnO nanorods, and the experimental growth of nanorods over electroformed Ni tubes.

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High aspect ZnO nanorod growth over electrodeposited tubes for photocatalytic degradation of EtBr dye

In this work, the potential of direct contact membrane distillation (DCMD) technology using novel MIL101(Fe) impregnated poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) mixed matrix membranes has been explored for dye removal from the textile industry wastewater. The influence of MIL101(Fe) impregnation on membrane performance was investigated by various morphological (SEM, AFM) and spectral techniques (XRD, FT-IR) along with transmembrane flux and dye rejection efficiency. Membrane performance over the range of feed temperature and the flow rate has also been explored for its applicability and suitability. The permeate flux grows exponentially with the feed temperature, whereas the dye rejection decreased with increased feed temperature. A decrease in boundary layer thickness at the membrane surface resulted in a linear increase in permeate flux with flow rate. The rejection was negligibly affected by the increase in flow rate. Among the fabricated membranes, M-M(0.5) (20% PVDF-HFP/0.5% MIL101(Fe)) membrane was adjudged the most suitable. Response surface methodology was used to investigate the influence of feed temperature and flow rate on permeate flux and dye rejection to optimize membrane performance. The optimized process parameters obtained were feed temperature: 353 K, flow rate: 40 l h−1. For these optimized input process parameters, the predicted responses were permeate flux: 6.75 l m−2 h−1 and dye rejection: 98.14%. Using the optimized parameters obtained from the RSM study, 24 h long run DCMD experiment was done to study membrane fouling on membranes using SEM and FT-IR analysis. The fabricated membranes showed great potential to treat real textile industry wastewater.

Novel MIL101(Fe) impregnated poly(vinylidene fluoride-co-hexafluoropropylene) mixed matrix membranes for dye removal from textile industry wastewater

Photocatalytic solar energy harvesting is considered as an excellent pathway to address the environmental energy dilemma. Due to the unique layered and band structure of bismuth oxyhalide (BiOX), it is an emergent class of photocatalysts which display adequate properties that promote the robust light response and may result in amplification of solar energy conversion. The current review will summarize the recent revolution in BiOX-based energy applications such as H2 and O2 evolution, as well as N2 fixation, and will present structural engineering and design solutions for improving energy conversion. Particularly, the preparation and structure tailoring of BiOX materials, as well as some other advanced techniques such as the building of Moire superlattices, heterojunctions, and tailoring the internal electric field, may boost the photocatalysis of BiOX materials. Additionally, various composite frameworks are discussed, emphasizing the importance of BiOX-based nanocomposites. Finally, the primary problems and potential for the material based on BiOX are discussed in terms of their future development. This review will provide a link between structural engineering and environmental applications and will provide a preferred path toward the novel material design based on BiOX for environmental and in particular, energy-related applications.

Recent advances in structural tailoring of BiOX-based 2D composites for solar energy harvesting

Hard chromium coatings have attracted much attention due to their strong tribological and corrosion performance. There is a global need to replace such coatings in industrial applications owing to technical problems, environmental concerns and legislation. Co-P electrodeposits are a promising alternative to hard chromium in a variety of engineering applications due to their appreciable microhardness and high corrosion resistance. Attractive magnetic, tribomechanical and electrical properties are evident together with excellent thermal stability. Environmentally acceptable process conditions may be used which allow controlled deposition on diverse workpieces across a wide scale. This review provides an overview of the influence of operational parameters, including type of current control, electrolyte composition, pH, current density and electrolyte agitation on the physicochemical and mechanical characteristics of the deposits. The incorporation of ceramic particles into Co-P electrodeposits to produce tailored composite coatings is also considered. An insight is given into the development of next generation alloy and composite deposits to replace hard chromium deposits from acidic Cr(VI) baths. Diverse applications for Co-P electrodeposits are considered and topics deserving further R & D are highlighted.

Electrodeposited Co-P alloy and composite coatings: A review of progress towards replacement of conventional hard chromium deposits

Perspective—Electrodeposition of Graphene Reinforced Metal Matrix Composites for Enhanced Mechanical and Physical Properties: A Review

Facile fabrication of hydrophobic ZnO nanostructured nickel microtubes through pulse electrodeposition as promising photocatalyst for wastewater remediation

Investigations on the effect of electrode gap variation over pulse-electrodeposition profile

Being an additive manufacturing process with a bottom-up approach, electrodeposition principle has opened up new avenues for the multiscale metallic deposition and because of its attainment of high precision and dimensional accuracy, it has equally received the attention of researchers as well as of various industrial sectors. Considering the utility of this inexpensive manufacturing process, the present review paper deals firstly with the fundamental principles and applications of both electrodeposition and electroforming processes along with the associated challenges and shortcomings. Thereafter, various energy field-assisted methods such as abrasive-assisted, ultrasonic-assisted, magnetic-assisted, localized, photo-assisted, and gravity-assisted electrodeposition/electroforming have been discussed. Research progress associated with these techniques has been elaborately explained along with their principle of operation. The fabrication of various functional coatings, nanostructures, nanocomposites using such hybrid techniques have also been explored. In short, this review article throws light on the immense manufacturing possibilities in the area of electrodeposition/electroforming that can be taken up as future scope in the areas of high-performance coatings, micro/nano-manufacturing and functional materials, etc. 

Hrudaya Jyoti Biswal

Papers

High aspect ZnO nanorod growth over electrodeposited tubes for photocatalytic degradation of EtBr dye

Perspective—Electrodeposition of Graphene Reinforced Metal Matrix Composites for Enhanced Mechanical and Physical Properties: A Review

Facile fabrication of hydrophobic ZnO nanostructured nickel microtubes through pulse electrodeposition as promising photocatalyst for wastewater remediation

Investigations on the effect of electrode gap variation over pulse-electrodeposition profile

Recent advances in energy field assisted hybrid electrodeposition and electroforming processes