Facile one-step synthesis of Ir-Pd bimetallic alloy networks as efficient bifunctional catalysts for oxygen reduction and oxygen evolution reactions

Nguyen, Anh Thi Nguyet,Shim, Jun Ho Elsevier 2018 Journal of Electroanalytical Chemistry Vol.827 No.-

<P><B>Abstract</B></P> <P>This paper introduces a facile one-step process to synthesize highly interconnected nanoporous Ir-Pd alloys supported on carbon that exhibit excellent bifunctional electrocatalytic activities for both the oxygen reduction and oxygen evolution reactions with reasonable stability in alkaline electrolytes. Nanoporous Pd networks with crystalline {111} faces were shown experimentally to serve mainly as active sites for the oxygen reduction reaction, whereas the Ir nanoparticles incorporated in the Pd nanoframe networks, where the optimized Ir:Pd ratio was 0.23:0.77 (<I>n</I> = 10), were responsible for the oxygen evolution reaction. Such three-dimensional architectures provide a high density of active sites for the oxygen electrochemical reaction and facilitate electron transport. More importantly, the nanoporous Ir-Pd alloy nanocomposites exhibited similar stability for the oxygen reduction reaction but superior catalytic activity to the commercial Pd catalyst in alkaline solutions. In addition, the materials were also highly active for the oxygen evolution reaction, e.g., a small overpotential at 10 mA cm<SUP>−2</SUP> (1.628 V vs. reversible hydrogen electrode), making it a high-performance bifunctional catalyst for both the oxygen electrochemical reaction. Rotating ring-disk electrode measurements showed that the oxygen reduction and oxygen evolution reactions on the Ir-Pd catalysts proceeded predominantly through the desired 4-electron pathway.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile one-step synthesis of a nanoporous Ir-Pd bimetallic alloy network. </LI> <LI> The composites exhibited bifunctional ORR/OER performance compared to Pd/C and Ir/C. </LI> <LI> Ir<SUB>23</SUB>Pd<SUB>77</SUB>/C exhibited the highest activity with good durability and overpotential. </LI> <LI> The properties of Ir<SUB>23</SUB>Pd<SUB>77</SUB>/C were due to its high surface area and high porosity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A highly active bifunctional electrocatalyst for the oxygen reduction and evolution reactions was developed based on a highly interconnected nanoporous Ir-Pd bimetallic alloy network.</P> <P>[DISPLAY OMISSION]</P>

Synergistic interaction and controllable active sites of phosphorus and nitrogen co-doped ethylenediaminetetraacetic acid as efficient cathodic catalysts for high performance oxygen reduction reaction

김관우,김주헌,김유진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Catalysts for oxygen reduction reaction (ORR) are crucial in fuel cells. Nitrogen (N) and phosphorus (P) co-doped porous carbon (C) materials have been prepared as a non-precious metal catalyst. The resulting material was capable of charge transfer via the coordination bond of cobalt (Co) and EDTA. In addition, redistribution of charge occurred due to co-doping of the N and P, which is advantageous for the oxygen reduction reaction (ORR). The as-prepared N and P co-doped mesoporous carbon (NPMPC) was characterized by a high average porosity and a high specific surface area. Furthermore, the NPMPC had a positive effect on ORR by allowing triple phases (gas-liquid-solid) to coexist in a wide range. The electrocatalytic activity of NPMPC for ORR in alkaline media, which was investigated using rotating disk electrode (RDE) technology, was better than that of a platinum (Pt/C) catalyst. Overall, NPMPC showed high efficiency and improved performance for oxygen reduction reaction.

Design of active bifunctional electrocatalysts using single atom doped transition metal dichalcogenides

Hwang, Jeemin,Noh, Seung Hyo,Han, Byungchan Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.471 No.-

<P><B>Abstract</B></P> <P>Single atom catalyst is designed to achieve high catalytic activity while extremely minimizing precious metal loadings for electrochemical energy conversion and storage applications. Using first-principles density functional theory calculations, we screen 48 combinations of single atom catalysts anchored at defective monolayer transition metal dichalcogenides (A<SUB>1</SUB>/TMD; A = Ni, Cu, Pd, Ag, Pt and Au; TM = Mo, W, Nb and Ta; D = S and Se). With established methodologies, we identify five best catalysts for each of oxygen reduction/evolution and hydrogen evolution reactions among the stable candidates. A scaling relation between the Gibb’s free energy for intermediates is figured out to understand the governing mechanism of single atom catalysts with varying transition metal dichalcogenides supports and to introduce key descriptor. Pt<SUB>1</SUB>/MoS<SUB>2</SUB> is proposed as the best bifunctional catalyst for oxygen reduction/evolution reaction. In addition, Pt<SUB>1</SUB>/NbSe<SUB>2</SUB> and Pt<SUB>1</SUB>/TaS<SUB>2</SUB> are promising candidates for oxygen and hydrogen evolution reactions. Treating the support itself as an active site for hydrogen evolution reaction, Pd<SUB>1</SUB>/NbS<SUB>2</SUB> and Pt<SUB>1</SUB>/NbS<SUB>2</SUB> are proposed as potential bifunctional catalysts toward oxygen reduction and evolution reaction, respectively. Conceptual design principle via high-throughput screening of single atom catalyst is demonstrated as a great approach to determine active and durable bifunctional single atom catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single atom catalysts with transition metal dichalcogenides supports were screened. </LI> <LI> Five best catalysts were selected for redox reactions of oxygen and hydrogen. </LI> <LI> Pt<SUB>1</SUB>/MoS<SUB>2</SUB> was identified as a great bifunctional single atom catalyst. </LI> <LI> Scaling law was proposed as the key to understand catalytic mechanism. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Mechanism in pH effects of electrochemical reactions: a mini-review

Liu Sibei,Wang Zhuowen,Qiu Shan,Deng Fengxia 한국탄소학회 2024 Carbon Letters Vol.34 No.5

pH plays a pivotal role in influencing various aspects of proton-coupled electron transfer (PCET) reactions in electrochemical systems. These reactions are affected by pH in terms of mass transport, electrochemical double layer (EDL) structure, and surface adsorption energy, all of which impact the overall electrochemical processes. This review article aims to provide a comprehensive understanding of the research progress made in elucidating the effects of pH on different electrochemical reactions, the hydrogen evolution reaction/hydrogen oxidation reaction (HER/HOR), oxygen reduction reaction/oxygen evolution reaction (ORR/OER), and carbon dioxide reduction reaction (CO2RR). To embark on this endeavor, we have conducted a bibliometric analysis to clearly outline of the research trends and advancements in the field concerning the pH effects. Subsequently, we present a systematic overview of the mechanisms governing these reactions, with a special focus on pH’s influence on both the proton and electron aspects. We conclude by discussing the current challenges in this area and suggesting future research avenues that could further our understanding of pH's role in electrochemical reactions.

Mesoporous iron sulfide nanoparticles anchored graphene sheet as an efficient and durable catalyst for oxygen reduction reaction

Gautam, Jagadis,Tran, Duy Thanh,Singh, Thangjam Ibomcha,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2019 Journal of Power Sources Vol.427 No.-

<P><B>Abstract</B></P> <P>The fabrication of low-cost, highly efficient, and earth-abundant electrocatalysts for oxygen reduction reaction is critical to produce clean and sustainable fuel through an electrochemical process. Herein, a facile hydrothermal technique is used for the synthesis of iron sulfide/graphene hybrid for oxygen reduction reaction. Morphological analysis of the resulting catalyst reveals that iron sulfide nanoparticles are homogeneously embedded on the surface of reduced graphene oxide sheet. Electrochemical analysis of the hybrid exhibits remarkably improved catalytic performance for oxygen reduction reaction while achieving half wave potential of +0.845 V and onset potential of +1.0 V (<I>versus</I> reversible hydrogen electrode), along with outstanding long-term stability under alkaline conditions. In addition, the methanol tolerance ability and stability of the hybrid exceed the benchmark platinum/carbon product in alkaline condition. These outstanding activities of the hybrid are attributed to the merits of the interaction between iron sulfide nanoparticles and graphene. The results suggest the practicability of metal sulfide as a low cost and efficient alternative catalyst of platinum for oxygen reduction reaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrothermal technique is used for fabricating a new iron sulfide/graphene hybrid. </LI> <LI> The interaction of mesoporous iron sulfide and graphene produces excellent activity. </LI> <LI> The hybrid outperforms Pt/C and other metal sulfide/graphene catalysts towards ORR. </LI> <LI> The hybrid's stability and methanol tolerance are superior to Pt/C product. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Evolution of silver to a better electrocatalyst: Water-assisted oxygen reduction reaction at silver chloride nanowires in alkaline solution

Kim, Su-jin,Lee, Seung-Cheol,Lee, Chongmok,Kim, Myung Hwa,Lee, Youngmi Elsevier 2018 Nano energy Vol.48 No.-

<P><B>Abstract</B></P> <P>Oxygen reduction reaction (ORR) is of great interest in various areas, including energy conversion. This paper presents the simple synthesis and characterization of one-dimensional silver halides nanowires (AgClNW and AgBrNW) as an electrocatalyst for ORR in alkaline media, as well as an investigation of the ORR pathway at AgCl. AgClNW and AgBrNW were prepared via a galvanic replacement reaction (GRR) between silver nanowires (AgNW) and a halide precursor. AgClNW exhibited excellent ORR catalytic activity that was comparable to or better than that for commercial Pt (20 wt% Pt loading on Vulcan carbon), demonstrating potential to replace Pt-based catalysts. A scanning electrochemical microscopy (SECM) analysis supports the existence of an associative ORR pathway at AgCl, and first-principles density functional theory (DFT) calculations suggest that the high ORR activity of AgCl is possibly attributed to the up-shifted Ag d-band center energy in AgCl as well as the assistance of adsorbed water molecules.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AgCl nanowires show an excellent catalytic activity for oxygen reduction reaction. </LI> <LI> AgCl nanowires are synthesized from Ag nanowires via galvanic replacement reaction. </LI> <LI> d-band center energy of Ag in AgCl is upshifted to become closer to that of Pt. </LI> <LI> Water adsorption on AgCl plays a critical role in the improved activity of AgCl. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Silver chloride nanowires show an excellent electrocatalytic activity for oxygen reduction reaction via water assistance.</P> <P>[DISPLAY OMISSION]</P>

산소환원반응 촉매용 질소 도핑된 탄소나노섬유의 제조

안건형,이은환,안효진,An, Geon-Hyoung,Lee, Eun-Hwan,Ahn, Hyo-Jin 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.6

N-doped carbon nanofibers as catalysts for oxygen-reduction reactions are synthesized using electrospinning and carbonization. Their morphologies, structures, chemical bonding states, and electrochemical performance are characterized. The optimized N-doped carbon nanofibers exhibit graphitization of carbon nanofibers and an increased nitrogen doping as well as a uniform network structure. In particular, the optimized N-doped carbon nanofibers show outstanding catalytic activity for oxygen-reduction reactions, such as a half-wave potential ($E_{1/2}$) of 0.43 V, kinetic limiting current density of $6.2mAcm^{-2}$, electron reduction pathways (n = 3.1), and excellent long-term stability after 2000 cycles, resulting in a lower $E_{1/2}$ potential degradation of 13 mV. The improvement in the electrochemical performance results from the synergistic effect of the graphitization of carbon nanofibers and the increased amount of nitrogen doping.

Synergistic interaction of P and N co-doping EDTA with controllable active EDTA-cobalt sites as efficient electrocatalyst for oxygen reduction reaction

Kwanwoo Kim,Jaehyun Wie,Jooheon Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.83 No.-

It is extremely advisable but challenging to develop cathodic catalyst for efficiently catalyzing the oxygenreduction reaction (ORR) in energy storage and conversion system. Nitrogen (N) and phosphorus (P) co-doped porous carbon (C) materials have been prepared as a non-precious metal catalyst. This synthesis wasachieved through pyrolysis of ethylenediaminetetraacetic acid, triphenylphosphine, melamine andCoCl2 6H2 O mixture. The resulting material was capable of efficiently charge transfer via the coordinationbond of cobalt (Co) and EDTA, that makes octahedral structure. In addition, redistribution of charge occurreddue to co-doping of the N and P, which is advantageous for the oxygen reduction reaction (ORR). The as-prepared N and P co-doped mesoporous carbon (NPMPC) was characterized by a high average porosityand ahigh specific surface area. Furthermore, the NPMPC had a positive effect on ORR by allowing triple phases(gas-liquid-solid) to coexist in a wide range. We have successfully fabricated electrochemical catalysts thathave not been reported previously. The electrocatalytic activity of NPMPC-0.6 (E onset:-0.08 V & Ehalf-wave:-0.136 V)for ORR in alkalinemediawasbetterthanPt/C(Eonset:-0.037 V &Ehalf-wave:-0.122 V).Overall,NPMPC-0.6 showed high efficiency and improved performance for oxygen reduction reaction.

Two-dimensional leafy Fe/N-doped carbon nanomaterials derived from Vitamin C-modified ZIF-L for efficient oxygen reduction reaction

Yating Zhang,Xiaobo Wang,Meng Chen,Pei He,Zhenghan Kong 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.5

Oxygen reduction reaction (ORR) is an important half-reaction in various energy devices such as fuel cells. Here, 2D dendriticFe/N co-doped carbon-based nanosheet composites (L-Fe-CNT@NCS-900) were obtained by high-temperature calcinationusing ZIF-L generated in the aqueous phase as a precursor and Vitamin C as a modifi er. It is found that the catalystscalcined at 900 possessed the large specifi c surface area and the pore size distribution graphs showed a narrow microporesize distribution centered at about 1.8 nm. Furthermore, the Fe-N-C species was detected, which further improved the ORRperformance as an active center. Thus, the L-Fe-CNT@NCS-900 calcined at 900 °C achieved the best ORR performance witha half-wave potential (E 1/2 ) of 0.85 V, and the hydrogen peroxide yield is only about 4% during the ORR process. Meanwhile,L-Fe-CNT@NCS-900 exhibited outstanding methanol resistance. This work proposes a new strategy for constructing anEfficient electrocatalysts for oxygen reduction reaction.

Design of Au core-Palladium alloy shell nanoparticle for oxygen reduction reaction in fuel cells

이예연,설용건,김형수,전유권,박명근,( Ulziidelger Byambasuren ),황주순 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Platinum based nanomaterials are usually used as the electrocatalysts for both the cathode(oxygen reduction) and anode(hydrogen oxidation) reactions. However, the high cost of Pt in cathode catalyst and the slow kinetics of oxygen reduction reaction (ORR) on Pt-based catalysts hinder the commercialization of fuel cells. Instead of using platinum, recent studies have focused on the discovery of non platinum electrocatalysts which have excellent electrocatalytic activity and chemical stability. In this study, we synthesized gold core/palladium-Cobalt alloy shell catalysts. The developed catalysts showed excellent catalytic activity than Au core/Pd shell catalysts. The structural information and electrocatalytic activities of the Au core/Pd-Ir alloy shell nanoparticles were analyzed by XRD, XPS, HR-TEM, ORR test and cyclic voltammetry(CV).