Yashwant Pratap Kharwar

Renewable energy-driven electrochemical CO2 reduction reaction (CO2RR) is reckoned as a potential pathway for establishing carbon-neutral chemical and fuel generation. Developing molecular complex-based heterogeneous electrocatalysts has emerged as a popular route for converting CO2 into specific C1 products, including CO, methanol, and formate. However, this approach has rarely culminated in the generation of a practically viable CO2 electrolyzer. In this work, a molecular Mn-carbonyl complex was designed with a specifically positioned multidentate triazole ligand scaffold. This complex was covalently anchored on graphene oxide (Mn-adpt@GO), which efficiently produced CO, HCOOH, and CH3OH from CO2 in aqueous media in an H-cell setup. The same Mn-adpt@GO material was deployed in an electrolyzer assembly to achieve ∼151 mA/cm2 current density with improved production of CH3OH during CO2RR over extended periods. This is a rare example of a heterogenized Mn-based molecular catalyst that facilitates the conversion of CO2 into CH3OH in an electrolyzer setup while retaining the molecular nature of the catalyst with appreciable stability. The in operando spectro-IR experiments indicated that this Mn-adpt@GO binds CO2 through the C-atom for the production of the major C1 products via the formation of a key surface-adsorbed COOH intermediate.

In response to the global demand for sustainable energy, water electrolysis powered by renewable sources has become a cornerstone technology for green hydrogen production. This work introduces a rapid, scalable, and substrate-integrated strategy for fabricating high-entropy alloy (HEA) catalyst layers for water splitting. HEAs comprising five or more principal elements in near-equimolar ratios offer unique characteristics such as lattice distortion, entropy stabilization, and multiple oxidation states, which enable the formation of highly active and stable catalytic centers.^1–3

High-entropy alloys (HEAs) offer substantial potential for electrocatalysis, attributed to phenomena such as lattice distortion, entropy stabilization, and the 'cocktail effect,' which facilitate the creation of numerous catalytic centres. However, a significant challenge remains in developing reliable and scalable fabrication methods capable of producing nanometer-level HEA coatings to minimize the loading of critical raw materials (CRMs) without compromising performance. Addressing this gap, we report a laser-directed approach for the synthesis of FeCoNiZnMn (FCNZM) HEA thin films onto nickel fibre (NFb) substrates. In addition to reducing the time and expense of heating needed for HEA preparation, this method offers strong HEA-substrate interactions, making it more active and durable in a harsh alkaline environment. As a result, the optimised FCNZM_2td_25p electrocatalyst demonstrates exceptional kinetics with an overpotential of 235.5 mV at 10 mA cm-2 and a favourable Tafel slope of 48 mV dec-1. This initial activity is matched by extraordinary stability, maintaining performance for over 100 hours at a high current density of 500 mA cm-2 and exceeding 160 hours in a single-cell configuration against an Ir/NFb benchmark. Post-mortem characterization via TEM, XPS, and XAS reveals that the superior durability originates from a dynamic restructuring process: the leaching of an unstable, Zn-rich surface layer preserves a stable, crystalline HEA framework while inducing the concurrent oxidation of Fe, Co, and Mn. These results demonstrate that our laser-directed approach provides a scalable pathway for low-loading, highly efficient transition-metal-based HEA anode, offering a viable PGM-free alternative for industrial alkaline water electrolysis.

Green hydrogen is increasingly acknowledged as a pivotal facilitator for the transition to a sustainable and renewable energy paradigm, presenting a clean alternative to conventional fossil fuels.

Defect engineering and morphology control are crucial in designing advanced transition metal oxide (TMO)-based electrocatalysts with superior activity towards the oxygen reduction reaction (ORR). Following this blueprint, one-dimensional mesoporous Ni–Co oxide spinel (NCO) nanowires were synthesized using a simple solvothermal method, where defects were introduced by modulating the intrinsic metal ion ratio. Extensive structural, morphological, and compositional characterization of the nanowires was performed using various experimental techniques. The nanowires exhibited appreciably large surface area and porous architecture. X-ray absorption and positron annihilation spectroscopic studies revealed an exclusive Co-ion vacancy in Co-deficient nanowires and oxygen vacancies in Co-rich and -deficient nanowires. X-ray photoelectron spectroscopic studies unraveled preferential surface enrichment of the Co-rich NCO catalyst with Co³⁺ and Ni²⁺ ions. Co-excess NCO catalysts showed outstanding electrocatalytic activity towards the ORR, with a Tafel slope as low as ∼50 mV per decade with an overpotential of ∼0.35 V, comparable to benchmark noble metal-based catalysts, and periodic DFT studies delineated the crucial role of excess Co on the catalyst surface for demonstrating such superior activity. The NCO catalyst with a Co/Ni content of 2.6 : 1 exhibited the highest selectivity towards O₂/H₂O conversion, and it was further deployed in a real-life operational alkaline anion exchange membrane fuel cell (AEMFC) at room temperature. This study successfully demonstrates practical utilization of judiciously designed NCO catalysts as suitable alternatives to noble metal-based catalysts in sustainable energy applications.

The electrochemical cells generate electrical energy from chemical reactions (i.e., Galvanic cells) or use electricity to conduct chemical reactions and produce chemicals (i.e., Electrolytic cells).^1,2 Electrolyzers are the electrolytic cells, where water (H₂O) electrolyzes to produce Hydrogen (H₂) and Oxygen (O₂), and CO₂ electrolyzes to produce various chemicals (such as CO, HCOOH, CH₃OH, C₂H₅OH, etc.), depending upon the selectivity and efficiency of the electrocatalysts.^3–5 Though various electrocatalysts for electrolyzers are developed but without well-designed, portable, and cost-effective electrolyzers, the overall commercialization is still limited. Herein, we are working to design new types of electrolytic cells to solve electrochemical problems and improve the overall performance of cells on a laboratory-to-industry scale.^6,7 We have designed a three-electrodes system cell where we can study electrochemical properties by variation in temperature of selectively working electrodes only (i.e., electrode materials), keeping all other systems at a constant temperature. In the second problem, we solved the ion migration issue from one compartment to another by minimizing the conventional H-cell's bar length (l).^8,9 We are developing stack electrolyzers that can be used as both H₂O and CO₂ electrolysis (Fig.1a-c). Figure 1

This work illustrates the practicality and economic benefits of employing a hetero‐interfaced electrocatalyst (CoS₂@CoFe‐LDH), containing cobalt sulphide and iron‐cobalt double‐layer hydroxide for large‐scale hydrogen generation. Here, the rational synthesis and detailed characterization of the CoS₂@CoFe‐LDH material to unravel its unique heterostructure are essayed. The CoS₂@CoFe‐LDH operates as a bifunctional electrocatalyst to trigger both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline seawater (pH 14.0) while showcasing low overpotential requirement for HER (311 mV) and OER (450 mV) at 100 mA cm⁻² current density. The identical CoS₂@CoFe‐LDH on either electrode in an H‐cell setup results in simultaneous H₂ and O₂ production from seawater with a ≈98% Faradaic efficiency with an applied potential of 1.96V@100 mA cm⁻². Next, this CoS₂@CoFe‐LDH catalyst is deployed on both sides of a membrane electrode assembly in a one‐stack electrolyzer, which retains the intrinsic bifunctional reactivity of the catalyst to generate H₂ and O₂ in tandem from alkaline seawater with an impeccable energy efficiency (50 kWh kg⁻¹‐of‐H₂). This electrolyzer assembly can be directly linked with a Si‐solar cell to produce truly green hydrogen with a solar‐to‐hydrogen generation efficiency of 15.88%, highlighting the potential of this converting seawater to hydrogen under solar irradiation.