Vembu Suryanarayanan

The escalating global demand for renewable energy sources and chemicals necessitates sustainable and resource-conscious production protocols that address future demands with a minimal environmental impact. The current study presents the viability of the AgCoAc@Ti3C2Tx-based catalyst for the CO2 fixation and oxygen evolution reaction (OER) reactions at mild operational parameters. Unlike previously reported MXene-based electrocatalysts, this work integrates a controlled electrodeposition methodology to create a synergistic AgCoAc active interface directly on a conductive MXene support. This tailored architecture leads to dual functionality, demonstrating enhanced performance in both electrocarboxylation and the OER, which has not been explored in similar systems. The multilayered Ti3C2Tx, having a large electroactive area, improves the physicochemical properties and charge-transfer pathways of AgCoAc moieties, restricting particle aggregation and stabilizing the composite structure. Meanwhile, AgCoAc anchored on Ti3C2Tx amplifies its conductive properties and provides dual metal coordination sites, elevating the catalyst efficiency for the electrocatalytic process. Electrocarboxylation of benzyl bromide with CO2 was carried out in a single-chamber cell comprising tetrabutylammonium bromide/acetonitrile (TBABr/ACN) as the electrolytic medium to generate phenylacetic acid (PAA). This synergy in AgCoAc@Ti3C2Tx yielded a maximum of 70% PAA at a current density of 50 mA cm–2 at room temperature. The performance of AgCoAc@Ti3C2Tx was further investigated for the OER in 1 M KOH, which showcased a low overpotential of 251 mV at 10 mA cm–2 with a Tafel slope of 93 mV dec–1, validating excellent OER performance. Hence, the developed protocol provides a facile catalyst preparation strategy for the dual-purpose multimetallic AgCoAc@Ti3C2Tx composite, which showcased admirable outcomes for electrocarboxylation as well as the OER.

Metal–organic frameworks are a novel class of crystalline porous materials with enormous application potential, consisting of metal nodes and organic linkers.

Because of their large specific surface area, high porosity, changeable pore size, and ordered pore arrangement, metal–organic frameworks (MOFs) are emerging as electrocatalysts in various fields of energy resources and bio-sensors. In this work, we report a one-pot synthesis of trimetallic MOFs (Co–Ni–Al-MOFs), as well as bimetallic MOFs (Co–Ni-MOFs, Co–Al-MOFs, and Ni–Al-MOFs) using Co, Ni, and Al metal salts and BTC and 4,4′-bipyridine as linkers, their characterization for surface morphology, functional group and elemental analysis using various analytical techniques and explored them as tri-modal catalysts for thiophene electrooxidation, water splitting and chemical reduction of 4-nitrophenol (4-NP). Electrochemical studies using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) on Co–Ni–Al-MOFs showed the lowest onset potential of 1.36 V with a lower Tafel slope of 181 mV dec⁻¹ and charge transfer resistance value (R_ct) of 447 Ω for the effective electrooxidation of thiophene. Further catalytic activity studies towards water splitting revealed that Co–Ni–Al-MOFs displayed superior catalytic activity towards the HER and the OER at lower overpotentials of 174 and 220 mV with Tafel slopes of 108 and 97 mV dec⁻¹ respectively, compared to other bimetallic MOFs with excellent long-term stability, as revealed by chronoamperometry (CA). The high catalytic activity of Co–Ni–Al-MOFs may be associated with their larger surface area and higher pore volume than those of the other bi-metallic MOFs, as studied by BET analysis, leading to innumerable redox-active sites towards electrochemical processes. Moreover, the catalytic activity of the as prepared catalysts was assessed towards the reduction of 4-NP to 4-aminophenol (4-AP), where Co–Ni–Al-MOFs exhibited exceptional activity with a minimum reduction time of 8 min bearing a high rate constant value.