@article {44172, title = {Nitrogen-doped graphene with a three-dimensional architecture assisted by carbon nitride tetrapods as an efficient metal-free electrocatalyst for hydrogen evolution}, journal = {Chemelectrochem}, volume = {4}, year = {2017}, month = {OCT}, pages = {2643-2652}, type = {Article}, abstract = {Current polymer membrane-based electrolyzers use Pt as a cathode catalyst for efficient reduction of water. The high cost of Pt-based catalysts forces researchers to develop alternative electrocatalysts. Here, a simple strategy has been proposed to synthesize a metal-free electrocatalyst for the hydrogen evolution reaction (HER) by high-temperature annealing of graphene oxide-coated melamine foam. The prepared catalyst possesses both structural and functional advantages with its three-dimensional (3D) interconnected arms of carbon nitride (CNx) backbone wrapped with nitrogen-doped graphene (N-RGO) sheets (CNx@N-RGO). CNx@N-RGO faces only a 193 mV overpotential to achieve a current density of 10mAcm(-2), which is far superior to the previously reported Pt-free systems. Along with the high exchange current density 34.7 x 10(-6)A cm(-2) and low Tafel slope of 54 mV dec(-1), CNx@N-RGO follows a Volmer-Heyrovsky mechanism for the HER. DFT calculations show that the synergy between CNx and N-RGO facilitates good electrical coupling between the two moieties and provides optimal binding to H+ ions on the catalyst that, in turn, results in efficient reduction of hydrogen ions.}, keywords = {carbon nitride, Density functional theory, electrocatalyst, hydrogen evolution reaction, nitrogen doped graphene}, issn = {2196-0216}, doi = {10.1002/celc.201700479}, author = {Gangadharan, Pranav K. and Unni, SreeKuttan M. and Kumar, Nandha and Ghosh, Prasenjit and Kurungot, Sreekumar} } @article {46052, title = {[MoS4](2-)-Intercalated NiCo-layered double hydroxide nanospikes: an efficiently synergized material for urine to direct H-2 generation}, journal = {ACS Applied Materials \& Interfaces}, volume = {11}, year = {2019}, month = {JUL }, pages = {25917-25927}, type = {Article}, abstract = {

Substituting the energy-uphill water oxidation half-cell with readily oxidizable urea-rich urine, a ground-breaking bridge is constructed, combining the energy-efficient hydrogen generation and environmental 6 protection. Hence, designing a robust multifunctional electrocatalyst is desirable for widespread implementation of this waste to fuel technology. In this context, here, we report a simple tuning of the electrocatalytically favorable characteristics of NiCo-layered double hydroxide by introducing [MoS4]2- in its interlayer space. The [MoS4]{\textquoteright} insertion as well as its effect on the electronic structure tuning is thoroughly studied via X-ray photoelectron spectroscopy in combination with electrochemical analysis. This insertion induces overall electronic structure tuning of the hydroxide layer in such a way that the designed catalyst exhibited favorable kinetics toward all the required reactions of hydrogen generation. This is why our homemade catalyst, when utilized both as a cathode and anode to fabricate a urea electrolyzer, required a mere X1.37 V cell potential to generate sufficient H2 by reaching the benchmark 10 mA cm-2 in 1 M KOH/0.33 M urea along with long-lasting catalytic efficiency. Other indispensable reason of selecting [MoS4]2- is its high-valent nature making the catalyst highly selective and insensitive to common catalyst-poisoning toxins of urine. This is experimentally supported by performing the real urine electrolysis, where the nanospike-covered Ni foam-based catalyst showed a performance similar to that of synthetic urea, offering its industrial value. Other intuition of selecting [MoS4]2- was to provide a ligand-based mechanism for hydrogen evolution half-cell [hydrogen evolution reaction (HER)] to preclude the HER-competing oxygen reduction. Another crucial point of our work is its potential to avoid the mixing of two explosive product gases, that is, H2 and O-2.

}, keywords = {hydrogen evolution reaction, Layered double hydroxide, nickel oxyhydroxide, sewage denitrification, urea oxidation reaction, urine/urea electrolysis}, issn = {1944-8244}, doi = {10.1021/acsami.9b06545}, author = {Nadeema, Ayasha and Kashyap, Varchaswal and Gururaj, Rakshitha and Kurungot, Sreekumar} } @article {46853, title = {Co@CoAl-layered double hydroxide/nitrogen-doped graphene composite catalyst for Al-H2O-based batteries: simultaneous hydrogen production and electricity generation}, journal = {ChemElectroChem}, volume = {7}, year = {2020}, month = {JUN}, pages = {2582-2591}, type = {Article}, abstract = {

Currently, the low energy efficiency of water electrolysis has compelled research toward the development of novel and energy-effective strategies for low-cost H-2 generation. In this context, we report a new concept of simultaneous H-2 and electricity generation by separating out the exothermic self-sustained Al-H2O reaction via electrochemistry. In addition, to catalyze the cathodic water reduction reaction, a single-pot and environmentally benign synthesis method is adopted. It results in the design of an electrocatalyst composed of Co@CoAl-layered double hydroxide core-shell nanospheres anchored over in situ generated N-doped graphene. Toward the water reduction reaction, the designed catalyst shows a negative voltage shift of mere around 113 mV with respect to the commercial Pt/C catalyst to reach the benchmark 10 mA cm(-2), with excellent stability of approximately 86 \% voltage retention after 12 h of continuous operation. The catalytic superiority of our material is evident when taken for battery-level testing; the fabricated device was able to deliver an average output voltage of around 0.95 V at a discharge current density of 5 mA cm(-2) along with H-2 liberation, which was also detected and quantified through gas chromatography.

}, keywords = {Al-H2O fuel cells, chronopotentiometry, core-shell structures, hydrogen evolution reaction, layered double hydroxides}, issn = {2196-0216}, doi = {10.1002/celc.202000502, Early Access Date = MAY 2020}, author = {Nadeema, Ayasha and Pandurang Kharabe, Geeta and Prakash Biswal, Dibya 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 {47380, title = {One-dimensional multichannel g-C3N4.7 nanostructure realizing an efficient photocatalytic hydrogen evolution reaction and its theoretical investigations}, journal = {ACS Applied Energy Materials}, volume = {4}, year = {2021}, month = {APR }, pages = {3118-3129}, type = {Article}, abstract = {

The emerging metal-free carbon nitride (C3N4) offers prominent possibilities for realizing the highly effective hydrogen evolution reaction (HER). However, its poor surface conductivity and insufficient catalytic sites hinder the HER performance. Herein, a one-dimensional vermicular rope-like graphitic carbon nitride nanostructure is demonstrated that consists of multichannel tubular pores and high nitrogen content, which is fabricated through a cost-effective approach having the final stoichiometry g-C3N4.7 for HER application. The present g-C3N4.7 is unique owing to the presence of abundant channels for the diffusion process, modulated surface chemistry with rich- electroactive sites from N-electron lone pairs, greatly reduced recombination rate of photoexcited exciton pairs, and a high donor concentration (4.26 x 10(17) cm(3)). The catalyst offers a visible-light-driven photocatalytic H-2 evolution rate as high as 4910 mu mol h(-1)g(-1) with an apparent quantum yield of 14.07\% at band gap absorption (2.59 eV, 479 nm) under 7.68 mW cm(-2) illumination. The number of hydrogen gas molecules produced is 1.307 x 10(15) s(-1) cm(-2), which remained constant for a minimum of 18 h of repeated cycling in the HER without any degradation of the catalyst. In density functional theory calculations, a significant change in the band offset is observed due to N doping into the system in favor of electron catalysis. The theoretical band gap of a monolayer of g-C3N4.7 was enormously reduced because of the presence of additional densities of states from the doped N atom inside the band gap. These impurity or donor bands are formed inside the band gap region, which ultimately enhance the hydrogen ion reduction reaction enormously.

}, keywords = {carbon nitride, Density functional theory, hydrogen evolution reaction, nitrogen-rich, Photocatalyst}, issn = {2574-0962}, doi = {10.1021/acsaem.0c02858}, author = {Antil, Bindu and Kumar, Lakshya and Ranjan, Ravi and Shenoy, Sulakshana and Tarafder, Kartick and Gopinath, Chinnakonda S. and Deka, Sasanka} } @article {47729, title = {Structure-tailored non-noble metal-based ternary chalcogenide nanocrystals for pt-like electrocatalytic hydrogen production}, journal = {ChemSusChem}, volume = {14}, year = {2021}, month = {AUG }, pages = {3074-3083}, type = {Article}, abstract = {A facile microwave-assisted strategy was employed to synthesize Ni3Bi2S2 nanocrystals. Variation in the synthesis conditions tuned the composition of monoclinic and orthorhombic phases of Ni3Bi2S2. The electrochemical hydrogen evolution activity of the catalyst with highest percentage of monoclinic phase demonstrated a negligible onset potential of only 24 mV close to that of state-of-the-art Pt/C with an overpotential as low as 88 mV. Density functional theory calculations predicted the monoclinic phase exhibit the lowest adsorption free energy corresponding to hydrogen adsorption (Delta GadsH*) and, therefore, the highest hydrogen evolution activity amongst the considered phases. The quasi-2D structure of monoclinic phase facilitated an increased charge-transfer between Ni and Bi, favoring the downward shift of the d-band center to enhance the catalytic activity.}, keywords = {charge transfer, electrocatalysis, hydrogen evolution reaction, Nanomaterials, ternary chalcogenides}, issn = {1864-5631}, doi = {10.1002/cssc.202100967}, author = {Sarkar, Shreya and Rawat, Abhishek and Das, Tisita and Gaboardi, Mattia and Chakraborty, Sudip and Vinod, C. P. and Peter, Sebastian C.} } @article {48391, title = {First-principles investigation of the electrocatalytic reduction of CO2 on zirconium-based single-, double-, and triple-atom catalysts anchored on a graphitic carbon nitride monolayer}, journal = {ACS Applied Nano Materials}, volume = {5}, year = {2022}, month = {OCT}, pages = {15409-15417}, type = {Article}, abstract = {

Conversion of carbon dioxide (CO2) with the help of an appropriate electrocatalyst with high stability, low onset potential, and exceptional selectivity is still one of the great tasks in the electrocatalytic reduction of CO2 to valuable chemicals. Herein, by means of systematic first-principles simulations, we investigate the CO2 reduction reaction (CO2RR) activity of zirconium-based single-, double-, and triple-atom (Zrn@C2N; n = 1-3) catalysts anchored on a graphitic carbon-nitride monolayer. In tune with the Sabatier principle, our results reveal that a moderate CO2 binding is vital for a low onset potential for the CO2RR. Consequently, based on rigorous free energy calculations, the Zr-based single-atom catalyst (SAC) is found to be most effective to convert CO2 to valuable products such as HCOOH and CH3OH. It is worth noting that CO2 reduction to HCOOH is spontaneous via the *HCOO intermediate on Zr1@C2N and involves a low onset potential of -0.23 V with respect to the reversible hydrogen electrode from the *COOH intermediate. Among all the catalysts evaluated computationally, the Zr SAC further reveals the lowest onset potential of -0.89 V for CH3OH formation. The results show that the Zr-based catalysts especially Zr1@C2N are found to effectively suppress the competitive hydrogen evolution reaction and promote the CO2RR. Moreover, all three catalysts exhibit high kinetic and thermal stability with negligible distortion due to which their structures can be retained very well up to 600 K. Thus, the current work may provide effective catalyst-design strategies for enhancing the electrocatalytic CO2RR performance of Zr-based materials.

}, keywords = {C1 and C2 products, CO2 reduction, first-principles simulations, hydrogen evolution reaction, onset potential, single-atom catalysts (SACs), Zrn@C2N catalysts}, doi = {10.1021/acsanm.2c03464}, author = {Hassan, Afshana and Anis, Insha and Shafi, Sadaf and Assad, Assif and Rasool, Anjumun and Khanam, Romana and Bhat, Gulzar Ahmad and Krishnamurty, Sailaja and Dar, Manzoor Ahmad} } @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 {48979, title = {Electrodeposited Co-Mn-Sn multicomponent alloy as an efficient electrocatalyst for hydrogen evolution reaction}, journal = {International Journal of Hydrogen Energy}, volume = {49}, year = {2024}, month = {JAN }, pages = {658-667}, type = {Article}, abstract = {

Despite having exciting material characteristics, the potential of multi-component alloys (MCAs) as electrocatalysts has not been fully realized. In this work, efficient binary and ternary MCA electrocatalysts containing inexpensive metals like Co, Mn and Sn have been prepared via the electrodeposition process. When tested for hydrogen evolution reaction (HER) in an alkaline medium, ternary Co-Mn-Sn alloy displayed enhanced activity with the lowest overpotential of 136 mV, a Tafel slope of 111 mV dec 1 and a very low charge transfer resistance, making it superior to the binary alloys (Co-Mn and Co-Sn), or the single metal catalysts (Co, Mn and Sn). The ternary alloy also displayed high electro-chemical and structural stability, making it a viable electrocatalyst for the hydrogen economy.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {Clean energy, electrocatalysis, Electrodeposition, hydrogen evolution reaction, Multi-component alloy, Non-platinum group metals}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2023.07.064}, author = {Chandran, M. Athira and Karumuthil, Subash Cherumannil and Singh, Ashutosh K. and Prasad, Bhagavatula L. V.} } @article {49617, title = {Graphitic carbon nitride supported boron quantum dots: a transition metal free alternative for di-nitrogen to ammonia reaction}, journal = {CHEMPHYSCHEM}, volume = {26}, year = {2025}, month = {MAR}, type = {Article}, abstract = {

Presently, a sustainable electrochemical Nitrogen Reduction Reaction (NRR) has been essentially found to be viable on transition metal-based catalysts. However, being cost-effective and non-corrosive, metal-free catalysts present an ideal solution for a sustainable world. Herein, through a DFT-based study, we demonstrate metal-free NRR catalysts, boron quantum dots with 13 atoms as a case study and their chemically modified counterparts when anchored on graphitic carbon nitride (g-C3N4) surface. The best catalyst among the studied, a silicon-doped boron quantum dot with a cagelike structure, is found to favour the dinitrogen to ammonia reaction pathway with a low liming potential and potential rate-determining step (PDS) of -0.11 V and 0.27 eV, respectively. The present work demonstrates as to how boron quantum dots, which are reported to be experimentally synthesised, can be exploited for ammonia synthesis when supported on the surface. These catalysts effectively suppress the HER, thus establishing its suitability as an ideal catalyst. The work also represents a futuristic pathway towards a metal-free catalyst for NRR.

}, keywords = {Boron quantum dot, Electro-catalyst, Graphitic carbon nitride, hydrogen evolution reaction, Limiting potential, metal free catalyst, Nitrogen Reduction Reaction}, issn = {1439-4235}, doi = {10.1002/cphc.202400766}, author = {Samudre, Nikhil S. and Krishnamurty, Sailaja} } @article {49815, title = {Highly active and durable MNS bifunctional electrocatalysts for enhanced anion exchange membrane water electrolysis}, journal = {Electrochimica Acta}, volume = {542}, year = {2025}, month = {DEC}, pages = {147408}, type = {Article}, abstract = {

The development of non-platinum group metal (non-PGM) electrocatalysts with performance comparable to their noble metal counterparts remains a significant challenge for overall water splitting. In this study, we demonstrate the performance of an Anion Exchange Membrane (AEM) water electrolyzer using a bifunctional, non-PGM electrocatalyst: reduced graphene oxide (rGO)-encapsulated MoS2/Ni3S2 (MNS) grown on a nickel foam (NF) substrate. The rGO/MoS2/Ni3S2 (rGO-MNS) electrode was synthesized via a facile, single-step hydrothermal method. For the hydrogen evolution reaction (HER), the rGO-MNS electrode exhibited a low overpotential of 94 mV at a current density of 100 mA cm-2, maintaining excellent stability over 50 h with a minimal degradation rate of 120 mu V h-1. In the case of the oxygen evolution reaction (OER), an overpotential of 410 mV was required to reach the same current density, with a similarly robust durability and a degradation rate of only 360 mu V h-1. When employed as symmetric electrodes for overall water electrolysis, the rGO-MNS system achieved a current density of 10 mA cm-2 at a cell voltage of 1.51 V, outperforming the benchmark Pt/C \& Vert;Ru/C catalyst pair, which required 1.58 V to reach the same performance. The enhanced electrocatalytic activity and durability are attributed to the conductive rGO encapsulation, which facilitates charge transfer and mitigates surface oxidation of the catalyst. These results present a promising strategy for designing cost-effective, durable, and highperformance non-PGM electrodes for AEM water electrolysis.

}, keywords = {Anion Exchange Membrane Water Electrolysis, Bifunctional Electrocatalyst, hydrogen evolution reaction, Oxygen Evolution Reaction, rGO-MNS}, issn = {0013-4686}, doi = {10.1016/j.electacta.2025.147408}, author = {Singh, Kailash and Yadav, Himanshu and Samdani, Kunda and Selvaraj, Kaliaperumal} } @article {49882, title = {Optimisation of metallic bismuth nanoparticle supported Pt-Bi(x\%)/C hybrid electrocatalyst for cost effective and efficient hydrogen production in alkaline media}, journal = {International Journal of Hydrogen Energy}, volume = {161}, year = {2025}, month = {AUG}, pages = {150699}, type = {Article}, abstract = {

The present study employed a simple mechanochemical method followed by 24-h ultrasonication to synthesize oxide-free metallic bismuth (Bi) nanoparticles. This was further used to synthesize a Pt-Bi(x\%)/C (NC-x) hybrid electrocatalyst for the hydrogen evolution reaction in alkaline media. X-ray photoelectron spectroscopy and contact angle measurements reveal, Bi modifies the electronic structure and surface morphology of the Pt/C electrocatalyst, thus enhancing reaction kinetics and active site availability. The relative three-electrode study reveals that optimised NC-20 electrocatalyst reduces the overpotentials by 10.44 \% and enhances the current density by 53 \% compared to commercial Pt/C. The practical applicability of the NC-20 electrocatalyst was studied with the 13 cm2 single cell anion exchange membrane electrolyser. The catalyst demonstrates promising performance where the current density of NC-20//IrO2 relatively increases by 22.6 \% compared to standard Pt/ C//IrO2, and shows continuous production and stable performance when monitored for 30 h.

}, keywords = {AEM, Bismuth nanoparticles, electrocatalyst, Full cell electrolysis, hydrogen evolution reaction, water electrolysis}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2025.150699}, author = {Dokhe, Revati and Ugale, Atul and Dube, Onkar and Varpe, Vaibhav and Galave, Chaitanya and Hattale, Gangadhar and Kadam, Rutuja and Virole, Vishal and Kumar, Ajay and Husale, Sudhir and Natu, Varun and Shevate, Rahul and Kanawade, Rajesh} }