Jain University, officially JAIN (Deemed-to-be University), is a private deemed-to-be-university located in Bangalore, India. Originating from Sri Bhagawan Mahaveer Jain College, it was conferred the deemed-to-be-university status in 2009.
Among a plethora of tactics, the electrochemical CO2-reduction method (ECO2RR) is a promising pathway to mitigate CO2 emissions and generate value-added chemicals simultaneously. Herein, a bimetallic NiO-HfO2-1 heterojunction catalyst was designed via the co-precipitation method, where the interfacial combination of NiO and HfO2 yields the remarkable synergistic effect due to strengthened interaction. The intrinsic structural and electronic properties were characterised using spectroscopic and analytical techniques. The as-designed catalyst was used as an electrode material for electrochemical analysis. NiO-HfO2-1 catalyst demonstrated a high current density (-33.68 mAcm- 2), a low overpotential and a low Tafel slope (83.38 mV dec-1), indicating that charge transfer through the electrode surface. An M-S plot gave evidence for the n-type semiconducting nature and the position of the band edges for the reduction of CO2. The catalyst was selective for formic acid with a Faradaic efficiency of over 96.08% in a long-term electrolysis test. The DFT computations promoted the experimental studies by showing that the NiO-HfO2-1 heterojunction interface is adept at lowering the energy barrier for CO2 activation. The combination of experimental electrochemical analysis, and DFT validation, which is used here to map the mechanistic route, reveals an intriguing catalyst design for sustainable energy conversion.
A hierarchically porous Sb2O3-Bi2O3 (AO-BiO) nano-leaf architecture was synthesized directly onto a nickel-foam via a simple in situ chemical route and explored as a multifunctional electrode for energy storage and water splitting applications. The synergistic coupling between Sb2O3 and Bi2O3, together with abundant oxygen vacancies and an open three-dimensional framework, enables rapid ion/electron transport and enhanced redox activity. As a symmetric supercapacitor electrode, AO-BiO delivers a high specific capacitance of 1738 F g-1 at 5 A g-1, an energy density of 149 Wh kg-1 at a power density of 9540 W kg-1, and 78% specific capacitance retention after 10 000 cycles. In addition, the AO-BiO electrode exhibits excellent bifunctional electrocatalytic activity for overall water splitting, requiring low overpotentials of 248 mV (OER) and 112 mV (HER) at 10 mA cm-2, with stable operation over 40 h. These results demonstrate a clear structure-property-performance relationship and highlight Sb2O3-Bi2O3 nanostructures as promising and durable electrodes for integrated energy storage and hydrogen production benefits.
As a Paradigm, the strategic integration of CO2 over an electrochemical reduction approach has become an enticing intellectual fulcrum area. This particular work involves the in-situ synthesis of CeO2 and MoO3 supported on activated carbon cloth (CeO2-MoO3@ACC-1) developed via an in situ hydrothermal method. The intrinsic features of the designed bimetallic oxide catalyst were investigated leveraging several analytical and spectroscopic methods. The CeO2-MoO3@ACC-1 catalyst is offered as an electrocatalyst for the electrochemical reduction of CO2 to formic acid. The proposed electrode material has a high current density (-55.13 mA cm-2), low overpotential (-0.78 V), and low Tafel slope value (46.43 mV dec-1), implying improved reaction kinetics. The designed catalyst exhibits strong selectivity for formic acid, with a faradaic efficiency of 90.30% at 1.3 V vs. RHE and improved stability over 3 h. The developed catalyst's superior electrocatalytic efficiency is reinforced by an intensive study of its microstructural characteristics using theoretical calculations. The UV-Visible measurement estimated the band gap of 2.35 eV, while Mott-Schottky characterizations identified the semiconductor type as n-type with a flat-band potential of 0.225 V, indicating good band edge positioning for effective CO2 conversion. The catalyst reveals a small crystalline size (12.5 nm), which promotes surface area and active sites that causes considerable atomic deviation and dislocation density, indicating a greater defect concentration. In a nutshell, results suggest a plausible reaction mechanism of electrochemical CO2 reduction, which steers the reaction pathway to formic acid, highlighting the potential of this catalyst for sustainable energy conversion.
The present work focuses on fabricating asymmetric supercapacitors (ASCs) using AC from coir fiber as the anode and nickel-cobalt double-layered hydroxide (NC-LDH) as the cathode material. The kinetic study of AC and NC-LDH was examined using a power law relationship and the Dunn model. The AC electrode showed a dominant surface-controlled charge storage mechanism of about 99.76%, with a very minimal diffusion-controlled process. The NC-LDH electrode exhibited the predominance of a pseudocapacitive process, with diffusion and surface-controlled charge storage mechanisms of about 93.50% and 6.49%, respectively. The surface areas of AC and NC-LDH were found to be 1330 and 52 m2/g, with total pore volumes of 0.81 and 0.38 cm3/g, respectively. The AC and NC-LDH demonstrated specific capacitances of 294 F/g and 586 F/g at current densities of 1 and 0.5 A/g, respectively, showing good cyclic performance and Coulombic efficiencies of about 99.61% and 98.96% over 5000 cycles in a three-electrode system. An asymmetric supercapacitor (ASC) device was fabricated, which displayed both diffusion- and surface-controlled processes of about 81.63 and 18.36% at a scan rate of 50 mV/s, and delivered a specific capacitance of 125.4 F/g at 0.5 A/g, offering an energy density of about 34 Wh/kg at a power density of 1300 W/kg. The device exhibited superior long-term cyclic stability, showing 92.38% capacitive retention and 99.85% Coulombic efficiency after 20,000 prolonged charge-discharge cycles. Thus, the kinetic study of the ASC device underscores the synergistic combination of AC and NC-LDH, thereby improving electrochemical performance through dual mechanisms (nonfaradaic and faradaic), which aid in increasing the overall capacitance of the ASC device.
In this work, the synthesis of the core-shell nickel-cobalt sulfide (NCS) catalyst was carried out via a direct sulfidation of nickel-cobalt glycerate (NC-g) through a template-free, facile, and cost-effective solvothermal method and applied for electrochemical CO2RR. The NCS material was thoroughly characterized using various analytical and spectroscopic techniques. The NCS catalyst exhibited distinctive structural and electronic properties, such as a narrow band gap, high conductivity, induced sulfur-defect-rich sites, and core-shell ball-in-ball nanospheres morphology. The electrocatalytic performance of the as-synthesized NCS was systematically compared with NC-g, NCO, NiS, and CoS catalysts. Among these, the NCS catalyst depicted superior electrocatalytic results, displaying a higher peak current density of -54.15 mA/cm2 and a low Tafel slope of 45.9 mV dec-1. The NCS catalyst demonstrated excellent selectivity with a Faradaic efficiency (FE %) for HCOOH production, reaching over 86.9% at an optimum potential of -0.5 V vs RHE. Comprehensive analyses of the reaction kinetics using Tafel slopes and electrochemical impedance spectroscopy measurements further designated rapid electron transfer kinetics and a low charge transfer resistance (R ct), enabling efficient CO2 conversion and long-term stability over a prolonged period of 24 h. The synergistic effect of Ni, Co, and S in the NCS matrix mutually enriched the eCO2RR performance by promoting H* formation, CO2 adsorption, and stabilization of HCOO* as an intermediate, supporting HCOOH formation. The microstructural and crystallographic analyses further supported the electrochemical results. These findings highlight that conductivity alone is inadequate for efficient CO2RR and that surface defect engineering and retention of the CO2-philic sites are acute. This work not only establishes NCS via a direct sulfidation of NC-g as an effective strategy through an anion-dependent effect (S2- vs O2- vs glycerate) for designing an efficient catalyst for CO2 to HCOOH conversion but also contributes to advancing scalable strategies for electrochemical CO2 reduction toward value-added products.
