Enhanced extraction of ethanol from ethanol-water mixture by pervaporation using PDMS membranes impregnated with the PDMS-derived silicon oxy-carbide particles Anil Verma, Yogendra Yadawa, Gunjan Kumar Agrahari, Karan Malik, Amit Ranjan Chemical Engineering Communications, 2026 In this work, we report that extraction of ethanol from the ethanol-water mixture using polydimethylsiloxane (PDMS) membranes is enhanced when the membrane is impregnated by the SiOC particles close to one side. SiOC particles with a high surface area (192 m2g−1) are prepared by a novel route in which a sponge of PDMS is wrapped inside an aluminum foil and subjected to a heat treatment at 550 °C. A 10% cross-linked and cured PDMS membrane is infused with these particles on one side up to a depth of 100 µm by exposing that side to a suspension of SiOC particles in di-iso-propylamine. Infusion leads to increased surface hydrophilicity on that side and a significantly altered pore size distribution in the membrane. We observed enhanced transport of ethanol as compared to water when infused membranes were used for pervaporation of a fifty-fifty mixture of ethanol water. We propose an explanation that the impregnated particles adsorb water molecules forming a water-rich region inside the membrane, which thereby affords a liquid phase diffusion of ethanol and enhances its transport as compared to neat membranes which offer only solid phase diffusion. SiOC modification increased ethanol–water selectivity by ∼150% compared to native PDMS.
Regeneration of Catalytic Activity of CuO-Cu2O/In2O3Nanocomposite towards Electrochemical Reduction of CO2by UV Light Treatment Pinki Devi, Arunima Singh, Karan Malik, Anil Verma, Saswata Bhattacharya, Jitendra Pratap Singh Journal of the Electrochemical Society, 2021 The deactivation of the electrocatalysts due to aging remains an issue, even though many electrocatalysts with very high faradaic efficiency (FE) have been developed. In the present work, we have put forth a facile approach for the regeneration of aged CuO–Cu 2 O/In 2 O 3 nanocomposite along with a possible mechanism for the regeneration of activity of aged catalysts towards electrochemical reduction by regaining their oxygen vacancies (V o ) defects concentration by ultra-violet (UV) light treatment. The photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and electrochemical reduction of CO 2 (ERC) measurements suggest that the decline in CO faradaic efficiency (FE CO ) can be attributed to the increase in V o concentration beyond an optimum level upon aging. From the state-of-the-art combined experimental and theoretical investigation, we conclude that the regeneration of the active sites in the aged electrocatalysts by UV light treatment helps in regaining the electrocatalytic activity towards ERC.
Syngas production from electrochemical reduction of CO2 at high current density using oxide derived Zn/Cu nanocomposite Karan Malik, Biju Mani Rajbongshi, Anil Verma Journal of Co2 Utilization, 2019 Reduction of CO2 in an electrochemical reactor may become a future technology for the production of syngas. This technology uses CO2 and water co-electrolysis and has the potential to produce variable CO/H2 ratio, which can become feedstock for various processes. However, developing an electrocatalyst selective for ERC is a great challenge. Further, high current density and low overpotential are essential for the electroreduction of the ERC. In this paper, oxide derived Zn/Cu electrocatalysts with different concentrations of Cu is reported using facile wet chemical synthesis route for the tunable syngas production. Physico-chemical analysis of the electrocatalysts revealed that by varying the concentration of Cu into the oxide derived Zn/Cu composite, fraction of Cu distributed into the ZnO crystal and composite form can be tunned. This inturn generates a synergic effect and reduces the charge transfer resistance towards ERC. By controlling the Cu concentration in the oxide derived Zn/Cu electrocatalyst CO/H2 ratio can be tunned over a wide range (0.84, 0.76, 0.25) at different current densities (20.4, 8.8, 37 mA/cm2). Oxide derived Zn/Cu electrocatalyst shows potential for electrochemical reduction of CO2 to syngas with tunnable CO/H2 ratio by utilizing renewable energy.
Selective electrochemical reduction of CO2 to CO on CuO/In2O3 nanocomposites: Role of oxygen vacancies Pinki Devi, Karan Malik, Ekta Arora, Saswata Bhattacharya, V. Kalendra, K. V. Lakshmi, Anil Verma, Jitendra P. Singh Catalysis Science and Technology, 2019 For the clean and sustainable development, sequestration of carbon dioxide (CO2) through electrocatalytic reduction to produce high-value industrial precursors, such as CO, is a promising avenue.
Effect of catalyst layer on electrochemical reduction of carbon dioxide using different morphologies of copper Karan Malik, Nardev Kumar Bajaj, Anil Verma Journal of Co2 Utilization, 2018 Electrochemical reduction of carbon dioxide (ERC) is one of the promising technologies for the renewable energy storage challenge and mitigation of the CO2 levels. Till now Cu has been found the best electrocatalyst for ERC but still the potential of Cu is not fully explored. This paper illustrates the effect of electrocatalyst layer formed by four different morphologies of cupper (nanorods, octahedral, spherical, and dendrite) with similar crystallite phases. Pre and post-ERC analysis of the catalyst in different environment shows that same crystal facet is formed at the end of ERC, indicating that the crystal rearrangement occurred during ERC is independent of the environment and does not promote any particular reaction. Nanorods form intercalated layers with an extended surface giving maximum faradaic efficiency of 26% at a lower cell voltage of −2.75 V. Dendrites forms porous layers, which are filled by the gas formed during ERC and thus decreases the active surface. However, the entrapped intermediates provide sufficient residence time and conditions for C2H4 and C2H6 formation. Spherical nanoparticles and octahedral nanoparticles formed a smooth, and thin layer with minimum faradaic efficiency towards ERC.
Electrochemical reduction of CO2 for synthesis of green fuel Karan Malik, Surya Singh, Suddhasatwa Basu, Anil Verma Wiley Interdisciplinary Reviews Energy and Environment, 2017 The depletion of increasing CO2 of the atmosphere and the generation of alternate fuel sources are among the biggest challenges being faced by the scientific community across the globe. This scenario has propelled work in the direction of utilization of CO2 by various methods. Electrochemical reduction of CO2 is one of the leading research areas that may be useful not only for the utilization of CO2 but also for the generation of green fuels and storage of renewable energy (solar or wind). However, the process is kinetically impeded and less selective toward a specific product and, therefore, requires efficient electrocatalysts. Much work has already been done in this field, and significant success has also been achieved. Hence, in this review paper, the potential of electrochemical reduction of CO2 for fuel generation is discussed, with special focus on electrocatalysts. The suitability of different electrocatalysts is addressed along with the possible scope for enhancing the efficiency of the process. WIREs Energy Environ 2017, 6:e244. doi: 10.1002/wene.244 For further resources related to this article, please visit the WIREs website.
Ag-Co bimetallic catalyst for electrochemical reduction of CO2 to value added products Surya Singh, Rajeev K. Gautam, Karan Malik, Anil Verma Journal of Co2 Utilization, 2017 Direct electrochemical reduction of carbon dioxide to values added products is one of the most promising and challenging techniques. Moreover, the lack of availability of efficient, selective and stable electrocatalysts is a major difficulty for efficient CO2 reduction. Various materials including metals, metal oxides, and metal complexes have been studied to increase the Faradaic efficiency, selectivity, and to reduce the energy input for the generation of hydrocarbons. Herein, we report a non-noble bimetallic electrocatalysts based on Ag-Co that is hardly evaluated for the electrochemical reduction of CO2 in-spite of the proven synergetic effect of bimetals for various chemical reactions. Therefore, the present study investigates the role of bimetallic electrocatalyst for the CO2 electrochemical reduction. A bimetal electrocatalyst is synthesized by Co and Ag metals to investigate the effect of the bimetal over gas phase CO2 electrochemical reduction. It is found that though the chosen metals are individually selective for the CO formation but the combination results in CH4 and C2H4 formation along with CO. The maximum Faradaic efficiency found for CH4 is 19.5% at 2 V using Ag-Co.
