High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions: Experimental Realization

Conversion of carbon dioxide into selective hydrocarbon using a stable catalyst remains a holy grail in the catalysis community. The high overpotential, stability, and selectivity in the use of a single-metal-based catalyst still remain a challenge. In current work, instead of using pure noble metals (Ag, Au, and Pt) as the catalyst, a nanocrystalline high-entropy alloy (HEA: AuAgPtPdCu) has been used for the conversion of CO2 into gaseous hydrocarbons. Utilizing an approach of multimetallic HEA, a faradic efficiency of about 100% toward gaseous products is obtained at a low applied potential (−0.3 V vs reversible hydrogen electrode). The reason behind the catalytic activity and selectivity of the high-entropy alloy (HEA) toward CO2 electroreduction was established through first-principles-based density functional theory (DFT) by comparing it with the pristine Cu(111) surface. This is attributed to the reversal in adsorption trends for two out of the total eight intermediates—*OCH3 and *O on Cu(111) and HEA surfaces

Easy scalable avenue of anti-bacterial nanocomposites coating containing Ag NPs prepared by cryomilling

The antibacterial coating is required in many applications such as water treatment plants, healthcare surfaces, air conditioners, doors, etc, and the synthesis process is needed to be scalable for technologically viability. The addition of an antibacterial agent in the coating endows the antibacterial action of the coating with extended durability. Therefore, metal nanoparticles are the best alternatives to antibiotics and other hazardous substances. The production of nanoparticles in large quantity and their distribution in the coating is the biggest challenge. The cryomilling technique is known to capable of large-scale production of metal nanoparticles (NPs). Among the other metals, Ag metal nanoparticles exhibit the remarkable antibacterial property. In the present investigation the pristine free standing Ag NPs were prepared by the cryomilling (milling at <123 K temperature) and ex-situ added in the silica-based SOL synthesized by silicon alkoxide hydrolysis and condensation. The Ag NPs embedded silica sol has been deposited over glass coverslips and aluminum panels using a dip-coating technique. They were characterized in coating stability, nanoparticles homogeneous distribution, and antibacterial/anti-fouling property against Staphylococcus aureus and Escherichia coli bacterial strains. The sol-gel nanocomposite coating embedded with Ag NPs has been found to exhibit excellent antifouling property against both the bacterial cell lines with the highest antibacterial efficiency of 92 and 90 % against E.coli and S. aureus, respectively

Multi-component (Ag–Au–Cu–Pd–Pt) alloy nanoparticle-decorated p-type 2D-molybdenum disulfide (MoS2) for enhanced hydrogen sensing

Molybdenum disulfide (MoS2) has emerged as a promising material for the development of efficient sensors. Here, we have exfoliated and decorated MoS2 flakes with the novel, single-phase multi-component silver–gold–copper–palladium–platinum (Ag–Au–Cu–Pd–Pt) alloy nanoparticles, popularly named High Entropy Alloy (HEA) nanoparticles, using facile and scalable low-temperature grinding, followed by the sonochemical method. It was found that the decoration of HEA nanoparticles imparts the surface-enhanced Raman scattering effect and reduction in the work function of the material from 4.9 to 4.75 eV as measured by UV photoelectron spectroscopy. This change in the work function resulted in a Schottky barrier between the gold contact and HEA decorated MoS2 flakes as a result of drastic changes in the surface chemical non-stoichiometry. The response to hydrogen gas was studied at temperatures in the range of 30 to 100 °C, and it showed an unusual p-type nature due to surface-adsorbed oxygen species. The nanoscale junction formed between HEA and MoS2 showed a ten-time increase in the response towards hydrogen gas at 80 °C. The experimental observations have been explained with DFT simulation showing more favourable hydrogen adsorption on HEA-decorated MoS2 resulting in an enhanced response

Nanofabrication route to achieve sustainable production of next generation defect-free graphene: analysis and characterisation

Abstract In the past two decades, graphene has been one of the most studied materials due to its exceptional properties. The scalable route to cost-effective manufacture defect-free graphene has continued to remain a technical challenge. Intrinsically defect-free graphene changes its properties dramatically, and it is a challenging task to control the defects in graphene production using scaled-down subtractive manufacturing techniques. In this work, the exfoliation of graphite was investigated as a sustainable low-cost graphene manufacturing technique. The study made use of a simple domestic appliance e.g., a kitchen blender to churn graphene in wet conditions by mixing with N-Methyl-2-pyrrolidone (NMP). It was found that the centrifugal force-induced turbulent flow caused by the rotating blades exfoliates graphite flakes to form graphene. The technique is endowed with a high yield of defect-free graphene (0.3 g/h) and was deemed suitable to remove 10% fluoride content from the water and color absorption from fizzy drinks