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Surface engineering of ZnO electrocatalyst by N doping towards electrochemical CO_(2) reduction

Journal of Energy Chemistry 2024年第1期88卷 71-81,I0002页

作者： Rohini Subhash Kanase Getasew Mulualem Zewdie Maheswari Arunachalam Jyoti Badiger Suzan Abdelfattah Sayed Kwang-Soon Ahn Jun-Seok Ha Uk Sim Hyeyoung Shin Soon Hyung Kang Department of Interdisciplinary Program for Photonic Engineering Chonnam National UniversityGwangju 61186Republic of Korea Graduate School of Energy Science and Technology(GEST) Chungnam National University99 Daehak-roYuseong-guDaejeon 34134Republic of Korea Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National UniversityGwangju 61186Republic of Korea Department of Advanced Chemicals and Engineering Chonnam National UniversityGwangju 61186Republic of Korea School of Chemical Engineering Yeungnam UniversityGyeongsan 38541Republic of Korea Department of Energy Engineering Korea Institute of Energy Technology(KENTECH)Naju 58217Republic of Korea

The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was ***,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping *** an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped ***,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR *** the ECR activity increased after a small amount of N doping,it decreased for higher N doping *** them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V *** hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.

关键词： ZnO N-doped ZnO Gas-diffusion electrode CO Selectivity Electrochemical CO_(2)reduction

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Facile Hot Gun Assisted Defect engineering of Mos2 Electrocatalyst for Hydrogen Evolution Reaction

SSRN

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SSRN 2024年

作者： Badiger, Jyoti Ganapati Arunachalam, Maheswari Kanase, Rohini Subhash Sayed, Suzan Abdelfattah Ahn, Kwang-Soon Kang, Soon Hyung Department of Interdisciplinary Program for Photonic Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National University Gwangju61186 Korea Republic of Department of Chemical Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemical Engineering Yeungnam University Gyeongsan712-749 Korea Republic of

Hydrogen evolution reaction (HER) is considered the most efficient method for hydrogen production using an effective electrocatalyst. Molybdenum disulfide (MoS2), with its unique 2D layered structure, is the most promising electrocatalyst. This is attributed to its flexibility, which facilitates the exploration of various MoS2 phases and properties. However, its low electrical conductivity and inert basal planes limit its effectiveness for HER. This study utilized a facile hot-gun approach to successfully introduce sulfur vacancies, simultaneously incorporating oxygen from the air, which partially occupied these vacancies. This process resulted in the formation of an intermediate MoOxSy phase, yielding a highly effective electrocatalyst. Exposure to the hot gun for a short duration led to several changes, notably expanding the interlayer spacing and altering the atomic S:O ratio from approximately 75% to 57%, primarily affecting the MoS2 structure. The optimal duration for hot-gun treatment was determined to be 30 s, enhancing electrochemical activity for HER, with an overpotential of -486 mV vs. RHE (briefly marked as VRHE) at a current density of 10 mA·cm-2 and Tafel slope of 224 mV·dec-1. © 2024, The Authors. All rights reserved.

关键词： Electrocatalysts

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Durable (> 50h) Bias-Free Solar Water-Splitting Cell Composed of N+P- Si/Nb2o5/Nipt Photocathode and W:Bivo4/Nicoo(Oh) Photoanode

SSRN

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SSRN 2023年

作者： Arunachalam, Maheswari Kanase, Rohini Subhash Badiger, Jyoti Ganapati Sayed, Suzan Abdelfattah Ahn, Kwang-Soon Ha, Jun-Seok Kang, Soon Hyung Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National University Gwangju61186 Korea Republic of Department of Interdisciplinary Program for Photonic Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Advanced Chemicals and Engineering Chonnam National University Gwangju61186 Korea Republic of School of Chemical Engineering Yeungnam University Gyeongsan38541 Korea Republic of

The development of photoactive material and design of tandem configuration in photoelectrochemical (PEC) water splitting has been regarded as one of the fastest emerging solar technologies. However, the recording solar-to-hydrogen efficiency (STH, %) still falls below expectations due to slow reaction kinetics and active material loss, which limits the large-scale hydrogen production. To suppress the high corrosion resistance required for optimum PEC activity, herein, a vertically oriented n+-doped p-Si photocathode (denoted as n+p-Si) is developed using alkali etching and phosphorization to improve bulk carrier separation. Then, the n+p-Si surface was passivated by thin crystalline niobium pentoxide (Nb2O5) nanolayer (~40 nm) with a facile spin-coating method, sufficiently providing the highest stability of ~70 h at 0 VRHE in the semiconductor/liquid junction between n+p-Si and electrolyte. Furthermore, the n+p-Si/Nb2O5 surface was electrochemically decorated with a nickel–platinum (NiPt) alloy composite as an efficient electrocatalyst to reduce the charge-transfer overpotential. The n+p-Si/Nb2O5/NiPt exhibited a high onset potential of ~0.62 V versus the reversible hydrogen electrode (RHE, abbreviated as VRHE) with a photocurrent density (J) of ~32 mA·cm−2 at 0 VRHE in 0.5 M H2SO4. As a counterpart, the bismuth vanadate (BiVO4) photoanodes have progressed significantly to improve bulk charge separation and injection by 2 wt% W doping as well as the electrodeposited NiCoO(OH) electrocatalysts, which delivered the excellent PEC performance with a maximum Jph of 5.6 mA·cm−2 at 1.23 VRHE. Finally, a solar water-splitting system composed of n+p-Si/Nb2O5/NiPt photocathode and W:BiVO4/NiCoO(OH) photoanode was fabricated in a PEC–PEC tandem configuration, and a stable STH conversion efficiency of 3.9% was achieved under an one sun illumination, accompanying with the stable H2/O2 production for 50 h. © 2023, The Authors. All rights reserved.

关键词： Charge transfer

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Highly Selective and Durable Co Production Above 90 % Via the Effective Morphology and Surface engineering of Zno Electrocatalysts

SSRN

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SSRN 2022年

作者： Kanase, Rohini Subhash Arunachalam, Maheswari Badiger, Jyoti Das, Pran Krisna Kang, Soon Hyung Department of Interdisciplinary Program for Photonic Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemistry Chonnam National University Gwangju61186 Korea Republic of Department of Advanced Chemicals and Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National University Gwangju61186 Korea Republic of

The present work demonstrates the morphological and Ag doping effects of ZnO electrocatalysts toward electrochemical CO2 reduction reaction (ECRR). To achieve this, three electrocatalysts, i.e., Nanosphere (0D), Nanorod (1D), and Nanosheet (2D), were synthesized via a facile hydrothermal method and their ECRR performance was evaluated. As an optimal electrocatalyst, the ZnO Nanorod showed a higher active surface area and roughness factor than Nanosphere and Nanosheet electrocatalysts. While a high surface area/oxygen defects found in the electrocatalyst led to the high selectivity of CO up to 68% at a high partial current density of 80 mA·cm-2,, maintaining the stable performance up to 4h. To enhance CO selectivity further, the surface engineering strategy was employed with Ag doping. With optimal Ag doping (1.0 at. %) in ZnO Nanorod electrocatalyst, it showed boosted CO selectivity of 91 % at a high partial current density of 93.4 mA·cm-2,. At the same time, it sustained a stable performance for up to 10h. This significant enhancement in ECRR performance could be attributed to i) high reaction rate, ii) fast mass transportation, and iii) an enhanced electronic conductivity. In particular, the very small amount of Ag doping could induce an electronic structure modification and generate more defective states, providing more active reaction sites for CO production and improving the ECRR. Based on these results, it can be said that simultaneous engineering of morphological features and Ag doping focusing on the specific surface state can be the best solution to improve ECRR along with product selectivity and activity. © 2022, The Authors. All rights reserved.

关键词： Electrocatalysts

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A Strategic Approach for Nanostructured Zn/Zno Based Electrocatalyst for Highly Selective Electrochemical Conversion of Co2 to Co

SSRN

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SSRN 2024年

作者： Kanase, Rohini Subhash Arunachalam, Maheswari Badiger, Jyoti Sayed, Suzan Abdelfattah Choi, Jonghoon Ha, Jun-Seok Kang, Soon Hyung Department of Interdisciplinary Program for Photonic Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemistry Education Chonnam National University Gwangju61186 Korea Republic of Department of Advanced Chemicals and Engineering Chonnam National University Gwangju61186 Korea Republic of Department of Chemistry Education and Optoelectronic Convergence Research Center Chonnam National University Gwangju61186 Korea Republic of

Electroreduction of carbon dioxide (CO2) directly facilitates the conversion of intermittent recycling into value-added chemicals and fuel, presenting a favorable strategy to resolve the energy and environmental crises caused by CO2 emissions. Therefore, there is a necessity to develop highly active and selective emerging electrocatalysts to perform electrochemical CO2 reduction (ECR) to carbon monoxide (CO). This work identifies a low-cost, earth-abundant, and non-toxic Zinc Oxide (ZnO-based) electrocatalyst as a promising electrocatalyst for CO selectivity. Initially, two different nanostructured Zinc (Zn) electrocatalysts, namely Nanosheet (NS) and Nanodendrites (ND), were synthesized by a facile electrodeposition (ED) method in ex situ mode using a standard cell and in situ mode using a gas diffusion electrode (GDE) based on the flow cell, and their ECR performances were compared. Here, the ND-Zn electrocatalysts, grown by the in situ ED method, showed a large electroactive surface area, demonstrating more efficient ECR activity toward CO production with a Faradaic efficiency (FECO) of 88.4% at –0.87 V versus reversible hydrogen electrode (VRHE). However, the NS-Zn electrocatalyst, grown by the ex situ ED method, exhibited a FECO of 65.6% at –0.98 VRHE at an applied current density of 100 mA cm–2. Accordingly, the enhanced electrochemical activity of the ND-Zn electrocatalyst can be attributed to the large surface area, which provides great adsorption capacity, and the Zn2+ sites. Moreover, the ND-Zn electrocatalyst stabilizes the intermediate step (CO*) during ECR, enhancing the reaction rate by reducing the activation energy. © 2024, The Authors. All rights reserved.

关键词： Electrocatalysts

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Low-Velocity-Favored Transition Radiation

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Physical Review Letters 2023年第11期131卷 113002-113002页

作者： Jialin Chen Ruoxi Chen Fuyang Tay Zheng Gong Hao Hu Yi Yang Xinyan Zhang Chan Wang Ido Kaminer Hongsheng Chen Baile Zhang Xiao Lin Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center College of Information Science & Electronic Engineering Zhejiang University Hangzhou 310027 China International Joint Innovation Center the Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering Technion-Israel Institute of Technology Haifa 32000 Israel Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore Department of Physics University of Hong Kong Hong Kong 999077 China Key Lab of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore 637371 Singapore

When a charged particle penetrates through an optical interface, photon emissions emerge—a phenomenon known as transition radiation. Being paramount to fundamental physics, transition radiation has enabled many applications from high-energy particle identification to novel light sources. A rule of thumb in transition radiation is that the radiation intensity generally decreases with the decrease of particle velocity v; as a result, low-energy particles are not favored in practice. Here, we find that there exist situations where transition radiation from particles with extremely low velocities (e.g., v/c<10−3) exhibits comparable intensity as that from high-energy particles (e.g., v/c=0.999), where c is the light speed in free space. The comparable radiation intensity implies an extremely high photon extraction efficiency from low-energy particles, up to 8 orders of magnitude larger than that from high-energy particles. This exotic phenomenon of low-velocity-favored transition radiation originates from the interference of the excited Ferrell-Berreman modes in an ultrathin epsilon-near-zero slab. Our findings may provide a promising route toward the design of integrated light sources based on low-energy electrons and specialized detectors for beyond-standard-model particles.

关键词： Atom or molecule scattering from surfaces Atomic & molecular collisions Cherenkov radiation Crystal optics Electron beams & optics Light-matter interaction Optical sources & detectors Optical transient phenomena Plasmonics

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Bulk-plasmon-mediated free-electron radiation beyond the conventional formation time

arXiv

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arXiv 2022年

作者： Tay, Fuyang Lin, Xiao Shi, Xihang Chen, Hongsheng Kaminer, Ido Zhang, Baile Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJUHangzhou Global Science and Technology Innovation Center College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX77005 United States International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Department of Electrical Engineering Technion-Israel Institute of Technology Haifa32000 Israel Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 637371 Singapore Centre for Disruptive Photonic Technologies Nanyang Technological University 637371 Singapore

Free-electron radiation is a fundamental photon emission process that is induced by fast-moving electrons interacting with optical media. Historically, it has been understood that, just like any other photon emission process, free-electron radiation must be constrained within a finite time interval known as the "formation time", whose concept is applicable to both Cherenkov radiation and transition radiation, the two basic mechanisms describing radiation from a bulk medium and from an interface, respectively. Here we reveal an alternative mechanism of free-electron radiation far beyond the previously defined formation time. It occurs when a fast electron crosses the interface between vacuum and a plasmonic medium supporting bulk plasmons. While emitted continuously from the crossing point on the interface — thus consistent with the features of transition radiation — the extra radiation beyond the conventional formation time is supported by a long tail of bulk plasmons following the electron’s trajectory deep into the plasmonic medium. Such a plasmonic tail mixes surface and bulk effects, and provides a sustained channel for electron-interface interaction. These results also settle the historical debate in Ferrell radiation, regarding whether it is a surface or bulk effect, from transition radiation or plasmonic oscillation. Copyright © 2022, The Authors. All rights reserved.

关键词： Plasmonics

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