@article {43870, title = {NiZn double hydroxide nanosheet-anchored nitrogen-doped graphene enriched with the gamma-NiOOH phase as an activity modulated water oxidation electrocatalyst}, journal = {Nanoscale}, volume = {9}, year = {2017}, month = {SEP}, pages = {12590-12600}, type = {Journal Article}, chapter = {12590-12600}, abstract = {

Herein, we report a facile solvothermal process to synthesize an active electrocatalyst for the oxygen evolution reaction (OER) in an alkaline medium by anchoring nanosheets of a NiZn double hydroxide over nitrogen doped reduced graphene oxide after enriching the system with the γ-NiOOH phase. This catalyst possesses a thin, porous and open layered structure, which makes the system more efficient and accessible for a better electrochemical water oxidation reaction. Moreover, we experimentally demonstrated that incorporation of Zn via a single-step solvothermal method provides an easy approach to obtain plenty of exposed γ-NiOOH phases to make the system more viable for OER with a small overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 44 mV per decade. In addition to this, the oxophilic nature of Zn in the (Zn)Ni-LDH/N-rGO catalyst helps to improve the long-term stability of the whole system. The obtained results open up possibilities for the design of future robust OER electrocatalysts by the use of very cheap and abundant materials like Ni and Zn in place of expensive Ir and Ru in the present commercial electrocatalysts.

}, keywords = {catalysis, Efficient Electrocatalyst, kinetics, Metal, Nickel-Hydroxide, oxide, Oxygen Evolution Reaction, performance, XPS Spectra, zinc}, issn = {2040-3364}, doi = {10.1039/c7nr02225e}, author = {Nadeema, Ayasha and Dhavale, Vishal M. and Kurungot, Sreekumar} } @article {44646, title = {Calixarene intercalated NiCo layered double hydroxide for enhanced oxygen evolution catalysis}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {6}, year = {2018}, month = {AUG}, pages = {9649-9660}, abstract = {

Water splitting provides a promising, sustainable way to resolve problems arising due to depleting fossil fuels. The success needs development of low-cost and high-performance electrode materials. The oxygen evolution reaction (OER) is a crucial reaction in water splitting. The combined Ni and Co oxide developed nanostructures having a small overpotential and fast kinetics of OER. They have drawn considerable attention, because of their theoretically high efficiency, high abundance, low cost, and environmental benignity in comparison with precious metal oxides, such as RuO2 and IrO2. However, the desired efficiency needs the developments of enhanced specific active area and conductivity. In the present communication, we address these issues. Specifically, exfoliation of layer double hydroxide (LDH) is applied to enhance the active surface area. The study reveals that intercalation by calixarene in NiCo LDH affords a multifunctional interlayer to deliver a large active surface area and fast electron transport toward the carbon nano-onion (CNO) support. It favorably lowers the overpotentials in OER (290 mV) and attains Tafel slope of 31 mV/decade. Enhanced conductivity is achieved using CNO as a support for the calixarene intercalated NiCo LDH. These developments offer a synergistic effect in achieving superior electrocatalytic activity for OER. This work gives insight into designing binder-free electrodes in alkaline media with good stability for advanced OER activity.

}, keywords = {Calixarene, electrocatalyst, Exfoliation, NiCo LDH, Oxygen Evolution Reaction}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.7b04788}, author = {Waghmode, Babasaheb J. and Gaikwad, Aarti P. and Rode, V, Chandrashekhar and Sathaye, Shivaram D. and Patil, Kashinath R. and Malkhede, Dipalee D.} } @article {44420, title = {Zirconium-substituted cobalt ferrite nanoparticle supported n-doped reduced graphene oxide as an efficient bifunctional electrocatalyst for rechargeable Zn-air battery}, journal = {ACS Catalysis}, volume = {8}, year = {2018}, month = {APR}, pages = {3715-3726}, type = { Article}, abstract = {

Solvothermal synthesis of zirconium-substituted cobalt ferrite nanoparticles was accomplished by the introduction of zirconium (Zr) in the spinel matrix to obtain a cost-effective and robust electrocatalyst that does not use noble metals. A variation in the cobalt ferrite structure CoFe2\−xZrxO4 with Zr (0.1\−0.4) substitution has significantly altered the overpotential for the electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), leading to an optimum composition of CFZr(0.3). The incorporation of the foreign Zr4+ ion in the cobalt ferrite spinel lattices has effectively enhanced the oxygen evolution reaction (OER) activity in comparison to the parent cobalt ferrite (CF) nanocrystals. However, a nominal change in the ORR current density has been observed due to Zr incorporation. For the OER, the Zr-substituted catalyst has shown a 40 mV negative shift in the overpotential in comparison with the CF nanoparticles at 10 mA/cm2 current density. Interestingly, the in situ grafting of Zr-substituted cobalt ferrite nanoparticles over N-doped reduced graphene oxide (CFZr(0.3)/N-rGO) results in remarkably enhanced performance during the ORR and moderately favored the OER with an overall potential difference (ΔE) of 0.840 V. The enhanced bifunctional electrocatalytic activity of the material is crucial for the fabrication of high-performance rechargeable Zn\−air batteries (ZABs). The prepared catalyst exhibited an overpotential of 80 mV for the ORR in comparison with the state-of-the-art (Pt/C) catalyst and an overpotential of 340 mV at 10 mA/cm2 current density for the OER from the standard value (1.23 V vs RHE). This potential bifunctional electrocatalyst has been employed as an electrode material for the fabrication of a primary ZAB, where it exhibited discharge capacities of 727 and 730 mAh/g at current densities of 20 and 30 mA/cm2 , respectively, under ambient conditions. The notable performance of the catalyst as a bifunctional material is observed during the cycling of the rechargeable ZAB. The prepared catalyst showed an increase of 200 mV in the overall operating overpotential after cycling for 10 cycles at 15 mA/cm2 in comparison to the 350 mV increase shown by the Pt/C catalyst.

}, keywords = {N-doped reduced graphene oxide, Oxygen Evolution Reaction, oxygen reduction reaction, zirconium-substituted cobalt ferrite}, issn = {2155-5435}, doi = {10.1021/acscatal.7b03823}, author = {Kashyap, Varchaswal and Kurungot, Sreekumar} } @article {46969, title = {Stress-induced electronic structure modulation of manganese-incorporated Ni2P leading to enhanced activity for water splitting}, journal = {ACS Applied Energy Materials}, volume = {3}, year = {2020}, month = {FEB}, pages = {1271-1278}, type = {Article}, abstract = {

The cornerstone of the emerging hydrogen economy is hydrogen production by water electrolysis with concomitant oxygen generation. Incorporating a third element in metal phosphides can tune the crystalline and electronic structure, hence improving the electrocatalytic properties. In this work, Mn-doped Ni2P with varying ratios of Mn and Ni has been explored as excellent catalysts for water splitting. A complete cell made of the best catalyst Ni1.5Mn0.5P electrodes showed low voltage of 1.75 V at a current density of 10 mA cm(-2) due to enhanced electrical conductivity, induction of tensile stress, enhanced electrochemical surface area, and increased electric dipole upon Mn incorporation.

}, keywords = {Electronic Structure, hydrogen evolution reaction, Oxygen Evolution Reaction, phosphides, water splitting}, issn = {2574-0962}, doi = {10.1021/acsaem.9b02097}, author = {Sarkar, Shreya and Dheer, Lakshay and Vinod, C. P. and Thapa, Ranjit and Waghmare, V. Umesh and Peter, Sebastian C.} } @article {47619, title = {Molecularly engineered graphene oxide anchored metal organic assembly: an active site economic bi-functional electrocatalyst}, journal = {FlatChem}, volume = {29}, year = {2021}, month = {SEP}, pages = {100269}, type = {Article}, abstract = {Low-temperature fuel cells are the most promising sustainable energy technology as they use hydrogen, an environmentally clean fuel. However, the sluggish kinetics of oxygen electrochemistry, a chronic issue, is holding them from commercialization. Herein, we address this issue through a molecular level design of a Graphene oxide anchored Metal Organic Molecular Assembly (G-MOMA) based catalyst. This non-precious metal catalyst consists of Ni and Fe ions ligated by graphene oxide supported terpyridine, a unique molecular assembly design that maximizes the utilization of active metal centers. This G-MOMA catalyst brings down an over potential (240 mV) for oxygen evolution reaction (OER) as close as that of the bench mark catalyst Ru/C with an impressive Tafel slope of 58 mV/dec and a cyclic stability of >30,000 cycles. G-MOMA excels in oxygen reduction reaction (ORR) too with an onset at 0.88 V (vs RHE). The remarkably stable G-MOMA catalyst surprises with an excellent bi-functionality towards both OER and ORR with an overall potential difference of mere 0.77 V, which is 180 mV and 70 mV lesser than the standard Pt/C and Ru/C catalysts, respectively. The G-MOMA catalyst is well in the activity range of the state-of-art bi-functional catalysts and yet cheaper by many folds.}, keywords = {Bi-functional electrocatalyst, graphene oxide, Metal organic molecular assembly, Oxygen Evolution Reaction, oxygen reduction reaction, terpyridine}, issn = {2452-2627}, doi = {10.1016/j.flatc.2021.100269}, author = {Jhajharia, Suman Kumari and Selvaraj, Kaliaperumal} } @article {47824, title = {Surface alteration driven bi-functional catalytic activity of alkali niobate-N doped graphene composite for exalted oxygen electrochemistry}, journal = {Applied Surface Science}, volume = {580}, year = {2022}, month = {APR}, pages = {152160}, type = {Article}, abstract = {In this work, we establish that surface reconstruction, oxygen vacancies {\textemdash}specifically those located on the catalyst surface, and high crystallinity can be effective in tuning the catalytic activity of perovskite oxides. We report a high-performance electrocatalyst with an orthorhombic perovskite structure (NaNbO3), having an anisotropic surface layer and high crystallinity that exhibits superior activity and durability for the bi-functional oxygen electrochemistry compared to that of a similar perovskite composition with an isotropic surface layer and low crystallinity. The improvement in the electrocatalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is mainly attributed to the formation of an easy diffusion path on the surface layer due to the ionic movements, enhanced intrinsic activity of the catalytic sites resulting from the higher crystallinity, high oxygen vacancies and a large electrochemically active surface area. The sole key parameter in achieving all the acquired characteristics is the annealing temperature. We believe that the straightforward method of bringing the desired combination of properties by just tweaking the annealing temperature is handy and energy-efficient, and hence easily adoptable.}, keywords = {Bi-functionality, N-doped graphene, Oxygen Evolution Reaction, oxygen reduction reaction, perovskite, Surface reconstruction}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2021.152160}, author = {Suman Kumari Jhajharia and Shashaank Gupta and Zinoy Manappadan and Kaliaperumal Selvaraj and Myoor K. Padmanabhan and Roop L. Mahajan} } @article {48951, title = {Distortion-induced interfacial charge transfer at single cobalt atom secured on ordered intermetallic surface enhances pure oxygen production}, journal = {ACS Nano}, volume = {17}, year = {2023}, month = {NOV }, pages = {23169-23180}, type = {Journal Article}, abstract = {

In this work, atomic cobalt (Co) incorporation into the Pd2Ge intermetallic lattice facilitates operando generation of a thin layer of CoO over Co-substituted Pd2Ge, with Co in the CoO surface layer functioning as single metal sites. Hence the catalyst has been titled Co-1-CoO-Pd2Ge. High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy confirm the existence of CoO, with some of the Co bonded to Ge by substitution of Pd sites in the Pd2Ge lattice. The role of the CoO layer in the oxygen evolution reaction (OER) has been verified by its selective removal using argon sputtering and conducting the OER on the etched catalyst. In situ X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopy demonstrate that CoO gets transformed to CoOOH (Co3+) in operando condition with faster charge transfer through Pd atoms in the core Pd2Ge lattice. In situ Raman spectroscopy depicts the emergence of a CoOOH phase on applying potential and shows that the phase is stable with increasing potential and time without getting converted to CoO2. Density functional theory calculations indicate that the Pd2Ge lattice induces distortion in the CoO phase and generates unpaired spins in a nonmagnetic CoOOH system resulting in an increase in the OER activity and durability. The existence of spin density even after electrocatalysis is verified from electron paramagnetic resonance spectroscopy. We have thus successfully synthesized intermetallic supported CoO during synthesis and rigorously verified the role played by an intermetallic Pd2Ge core in enhancing charge transfer, generating spin density, improving electrochemical durability, and imparting mechanical stability to a thin CoOOH overlayer. Differential electrochemical mass spectrometry has been explored to visualize the instantaneous generation of oxygen gas during the onset of the reaction.

}, keywords = {DEMS, interfacial charge transfer, Intermetallic, long-termstability, operando spectroscopic techniques, Oxygen Evolution Reaction, structuraldistortion}, issn = {1936-0851}, doi = {10.1021/acsnano.3c09680}, author = {Mondal, Soumi and Riyaz, Mohd and Bagchi, Debabrata and Dutta, Nilutpal and Singh, Ashutosh Kumar and Vinod, Chathakudath P. and Peter, Sebastian C.} } @article {48332, title = {Thermally constructed stable Zn-doped NiCoOx-z alloy structures on stainless steel mesh for efficient hydrogen production via overall hydrazine splitting in alkaline electrolyte}, journal = {Journal of Colloid and Interface Science}, volume = {640}, year = {2023}, month = {JUN }, pages = {737-749}, type = {Article}, abstract = {

Hydrogen has a high energy density of approximately 120 to 140 MJ kg(-1), which is very high compared to other natural energy sources. However, hydrogen generation through electrocatalytic water splitting is a high electricity consumption process due to the sluggish oxygen evolution reaction (OER). As a result, hydrogen generation through hydrazine-assisted water electrolysis has recently been intensively investigated. The hydrazine electrolysis process requires a low potential compared to the water electrolysis process. Despite this, the utilization of direct hydrazine fuel cells (DHFCs) as portable or vehicle power sources necessitates the development of inexpensive , effective anodic hydrazine oxidation catalysts. Here, we prepared oxygen-deficient zinc-doped nickel cobalt oxide (Zn-NiCoOx-z) alloy nanoarrays on stainless steel mesh (SSM) using a hydrothermal synthesis method followed by thermal treatment. Furthermore, the prepared thin films were used as electrocatalysts , the OER and hydrazine oxidation reaction (HzOR) activities were investigated in three-and two-electrode systems. In a three-electrode system, Zn-NiCoOx-z/SSM HzOR requires-0.116 V (vs RHE) potential to achieve a 50 mA cm(-2) current density, which is dramatically lower than the OER potential (1.493 V vs RHE). In a two-electrode system (Zn-NiCoOx-z/SSM(-)IIZn-NiCoOx-z/SSM(+)), the overall hydrazine splitting potential (OHzS) required to reach 50 mA cm(-2) is only 0.700 V, which is dramatically less than the required potential for overall water splitting (OWS). These excellent HzOR results are due to the binder-free oxygen-deficient Zn-NiCoOx-z/ SSM alloy nanoarray, which provides a large number of active sites and improves the wettability of cat-alysts after Zn doping. (C) 2023 Elsevier Inc. All rights reserved.

}, keywords = {Hydrazine Oxidation Reaction, hydrogen evolution reaction, Oxygen Evolution Reaction, Oxygen-Deficient Materials, Zinc Doping}, issn = {0021-9797}, doi = {10.1016/j.jcis.2023.02.142}, author = {Kashale, Anil Ashok and Rasal, Akash Sanjay and Hsu, Fei-Chien and Chen, ChangChun and Kulkarni, Sayali Nitin and Chang, Chun Hao and Chang, Jia-Yaw and Lai, Yuekun and Chen, I. -Wen Peter} } @article {49324, title = {Advanced 3D network of N-doped graphitic carbon with FeNi alloy embedding for high-performance rechargeable Zn-air batteries}, journal = {Advanced Sustainable Systems}, volume = {8}, year = {2024}, month = {JUL}, type = {Article}, abstract = {

Despite the significant progress in Zn-air batteries (ZABs), their widespread use in the rechargeable sector is hindered due to the scarcity of efficient bifunctional oxygen catalysts that can catalyze both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). To address this, an ORR/OER bifunctional electrocatalyst is designed with ultrafine alloyed FeNi nanoparticles encapsulated in a 3D interconnected N- doped carbon network structure, featuring a carbon nitride backbone enclosed in graphitic carbon. The FeNi electrocatalyst (3DFeNiPDC) showed good bifunctional activity toward both ORR and OER in the basic medium with a low overpotential value of 30 mV for ORR and 6 mV for OER compared to its state-of-the-art counterparts Pt/C, and RuO2, respectively. Utilizing 3DFeNiPDC in a rechargeable Zn-air battery (RZAB) yields an open circuit voltage (OCV) of 1.35 V, a maximum power density of 232 mW cm-2, and an energy density of 707 W h kg-1. Additionally, a flexible RZAB employing 3DFeNiPDC demonstrates an OCV of 1.4 V with various bending angles. These finding suggest 3DFeNiPDC as a viable alternative to noble metal-based RZABs, offering superior bifunctional electrocatalytic activity and stability, particularly with its enhanced air-breathing properties facilitating improved operability under practical conditions. The bifunctional electrocatalytic activity of FeNi alloy nanoparticles embedded in a 3D- interconnected N-doped graphitic carbon (3DFeNiPDC) for both oxygen reduction and oxygen evolution is studied. The 3D architecture and core-shell characteristics of FeNi alloy nanoparticles provide better activity and stability for oxygen electrocatalysis. The electrocatalytic activity of 3DFeNiPDC has been exploited for liquid-state and solid-state flexible rechargeable zinc-air batteries. image

}, keywords = {Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable flexible zinc-air battery}, issn = {2366-7486}, doi = {10.1002/adsu.202400012}, author = {Pandikassala, Ajmal and Kurian, Maria and Gangadharan, Pranav K. and Torris, Arun and Kurungot, Sreekumar} } @article {49367, title = {Aluminium, nitrogen-dual-doped reduced graphene oxide Co-existing with cobalt-encapsulated graphitic carbon nanotube as an activity modulated electrocatalyst for oxygen electrocatalyst for oxygen electrochemistry applications}, journal = {Small}, volume = {20}, year = {2024}, month = {AUG}, type = {Article}, abstract = {

There is a rising need to create high-performing, affordable electrocatalysts in the new field of oxygen electrochemistry. Here, a cost-effective, activity-modulated electrocatalyst with the capacity to trigger both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in an alkaline environment is presented. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with cobalt-encapsulated carbon nanotube units. Based on X-ray Absorption Spectroscopy (XAS) studies, it is established that the superior reaction kinetics in Al, Co/N-rGCNT over their bulk counterparts can be attributed to their electronic regulation. The Al, Co/N-rGCNT performs as a versatile bifunctional electrocatalyst for zinc-air battery (ZAB), delivering an open circuit potential approximate to 1.35 V and peak power density of 106.3 mW cm-2, which are comparable to the system based on Pt/C. The Al, Co/N-rGCNT-based system showed a specific capacity of 737 mAh gZn-1 compared to 696 mAh gZn-1 delivered by the system based on Pt/C. The DFT calculations indicate that the adsorption of Co in the presence of Al doping in NGr improves the electronic properties favoring ORR. Thus, the Al, Co/N-rGCNT-based rechargeable ZAB (RZAB) emerges as a highly viable and affordable option for the development of RZAB for practical applications. This manuscript reports the development of a new bifunctional catalyst that exhibits high activity and stability under practical operating conditions. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with the in situ formed cobalt-encapsulated CNT units is synthesized by a scalable pyrolysis method in an inert Ar atmosphere. The developed electrocatalyst achieved enhanced the oxygen reduction reaction (ORR) and the oxygen evolution reaction OER activity as a result of the favorable synergistic modulations and the system can serve as a process-friendly air-electrode for rechargeable zinc-air battery (RZAB). image

}, keywords = {Al, Bifunctional catalyst, DFT study, encapsulated structure, N-dual doping, Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable zinc-air battery, X-ray absorption spectroscopy}, issn = {1613-6810}, doi = {10.1002/smll.202400012}, author = {Kharabe, Geeta Pandurang and Barik, Sidharth and Veeranmaril, Sudheesh Kumar and Nair, Aathira and Illathvalappil, Rajith and Yoyakki, Athira and Joshi, Kavita and Vinod, Chathakudath Prabhakaran and Kurungot, Sreekumar} } @article {49203, title = {Breaking the inactivity of MXenes to drive Ampere-level selective oxygen evolution reaction in seawater}, journal = {MATERIALS SCIENCE \& ENGINEERING R-REPORTS}, volume = {160}, year = {2024}, month = {SEP}, pages = {100835}, type = {Review}, keywords = {2D heterostructures, Metal-organic framework, Oxygen Evolution Reaction}, issn = {0927-796X}, doi = {10.1016/j.mser.2024.100835}, author = {Gbadamasi, Sharafadeen and Loomba, Suraj and Haris, Muhammad and Khan, Muhammad Waqas and Maibam, Ashakiran and Mousavi, Seyed Mahdi and Mahmud, Sofiu and Thomsen, Lars and Tadich, Anton and BabaRao, Ravichandar and Xian, Jian and Mahmood, Nasir} } @article {49504, title = {Pt-based 3D electrocatalyst with process-friendly features for PEMFCs possessing fast activation and improved mass-transfer properties}, journal = {Advanced Sustainable Systems}, volume = {9}, year = {2025}, month = {APR}, type = {Article}, abstract = {

Polymer-electrolyte-membrane fuel cells (PEMFCs) face the challenges like slow oxygen reduction reaction (ORR) kinetics and limited mass transport at high current densities, which affects their performance. The efficient water removal from the cathode is essential to improve oxygen diffusion. Addressing this, a catalyst is presented with platinum (Pt) nanoparticles distributed within a 3D carbon network (Pt/3DPDC) derived from the polydopamine-coated melamine foam. This unique architecture enhances Pt utilization and water management due to its high porosity and ample free spaces, providing a process-friendly feature for the electrode under PEMFC conditions. The pores and accessible texture of the 3D polydopamine derived carbon (3DPDC) framework facilitate ionomer uptake during the electrode fabrication, extending the active triple-phase boundary and improving the membrane electrode assembly (MEA) performance. The high porosity of Pt/3DPDC is mitigated by adding a small amount of commercial fuel cell catalayst (Pt/C), which maintains the effective catalyst number density per unit area by utilizing the excess porosity of the 3DPDC framework. This controlled interplay of the unique catalyst structure and spatially confined distribution of Pt/C within the Pt/3DPDC framework offers fast activation, reduced electrode flooding, and improved current densities across the operating potential window. This carefully engineered catalyst, designed through bottom-up strategies, is a promising electrocatalyst for practical PEMFC applications.

}, keywords = {Oxygen Evolution Reaction, oxygen reduction reaction, rechargeable flexible zinc-air battery}, issn = {2366-7486}, doi = {10.1002/adsu.202400904}, author = {Pandikassala, Ajmal and Nadumattuvayil, Varsha and Singh, Mayank U. and Jadhav, Swapnil D. and Yoyakki, Athira and Kurungot, Sreekumar} }