Recent Advancements in Ascribing Several Platinum Free Electrocatalysts Pertinent to Hydrogen Evolution from Water Reduction.

The advancement of a sustainable and scalable catalyst for hydrogen production is crucial for the future of the hydrogen economy. Electrochemical water splitting stands out as a promising pathway for sustainable hydrogen production. However, the development of Pt-free electrocatalysts that match the energy efficiency of Pt while remaining economical poses a significant challenge. This review addresses this challenge by highlighting latest breakthroughs in Pt-free catalysts for the hydrogen evolution reaction (HER). Specifically, we delve into the catalytic performance of various transition metal phosphides, metal carbides, metal sulphides, and metal nitrides toward HER. Our discussion emphasizes strategies for enhancing catalytic performance and explores the relationship between structural composition and the performance of different electrocatalysts. Through this comprehensive review, we aim to provide insights into the ongoing efforts to overcome barriers to scalable hydrogen production and pave the way for a sustainable hydrogen economy.

pH dependent electro-oxidation of arsenite on gold surface: Relative kinetics and sensitivity.

A detailed kinetic investigation of As(III) oxidation was performed on gold surface within pH between ∼3.0 and ∼9.0. It was found that the As(III) oxidation on the gold surface follows a purely adsorption-controlled process irrespective of pH. The evaluated adsorption equilibrium constant decreased from 3.21 × 105 to 1.61 × 105 mol L-1 for acidic to basic medium, which implies the strong affinity of the arsenic species in the acidic medium. Besides, the estimation of Gibbs free energy revealed that an acidic medium promotes arsenic oxidation on gold surface. In mechanistic aspect, the oxidation reaction adopts a stepwise pathway for acidic medium and a concerted pathway for neutral and basic medium. From the substantial kinetic evaluation, it is established that a conducive and compatible environment for the oxidation of arsenic was found in an acidic medium rather than a basic or neutral medium on gold surface. Besides, in sensitivity concern, neutral and highly acidic medium is quite favourable for the arsenite oxidation on gold surface.

Photocatalytic degradation of chlorazol yellow dye under sunlight irradiation using Ce, Bi, and N co-doped TiO2 photocatalyst in neutral medium.

Chlorazol yellow (CY) is a commonly used anionic, toxic, mutagenic, and potentially carcinogenic azo dye, which is menacing to the environment, aquatic system, food chain, and human health as well. To remove CY dye molecules from an aqueous medium, a series of Ce, Bi, and N co-doped TiO2 photocatalysts were prepared by varying the composition of the dopants. Under sunlight irradiation, the resultant 5 wt% (Ce-Bi-N) co-doped TiO2 composite catalyst was found to show the best catalytic activity. Hence, the required characterization of this catalyst was performed systematically using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques. From the thorough investigation, it is revealed that the CY molecules reached adsorption-desorption equilibrium onto the surface of the catalyst within 30 min following second-order kinetics. Herein, the catalyst attained 97% degradation when exposed to sunlight at neutral (pH ~ 7, [CY] = 5 mg L-1) medium. The developed catalyst can destruct CY molecules with a maximum rate of 23.1 µg CY g-1 min-1 and the photodegradation kinetics follows first-order kinetics below 23.5 mg L-1, a fractional order between 23.5 and 35.0 mg L-1, and a zeroth order above 35.0 mg L-1 of CY concentration. Finding from scavenging effect implies that [Formula: see text] and [Formula: see text] radicals have significant influence on the degradation. A suitable mechanism has been proposed with excellent stability and verified reusability of the proposed photocatalyst.

Optimisation and Stability of Rh Particles on Noble Metal Films Immobilised on H+ Conducting Solid Polymer Electrolyte in Attaining Efficient Nitrate Removal.

During the electrocatalytic reduction of nitrate, nitrite is often evolved as a product along with ammonia due to the sluggish nitrite-to-ammonia conversion process compared to the nitrate-to-nitrite conversion step. Rhodium metal has been proven to enhance nitrite-to-ammonia conversion rates, yielding ammonia as the only final product. In the present article, we have shown how effectively Rh nanoparticles immobilized on Pt and Pd films deposited on H+ conducting Nafion-117 membranes eliminate intermediate nitrite ions during the progress of the nitrate reduction reaction in a flow type reactor. In this research, we also demonstrated the optimization of Rh nanoparticles on the cathode surface to attain effective nitrate reduction along with a reproducibility check. The dissolution of loosely held Rh nanoparticles on the cathodic surface was observed, which tends to be redeposited during cathodic electrolysis, causing stable performance. Finally, Tafel analysis was performed to show the relative kinetic feasibility of the Rh-modified Pt and Pd electrodes in attaining nitrate reduction reactions in neutral medium.