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2. Machine Learning Assisted Design and Optimization of Transition Metal-Incorporated Carbon Quantum Dot Catalysts for Hydrogen Evolution Reaction

Author

Nguyen, Duong Nguyen, Kim, Min-Cheol, Baeck, Unbeom, Lim, Jaehyoung, Shin, Namsoo, Kim, Jaekook, Choi, Heechae, Park, Ho Seok, Sim, Uk, and Kim, Jung Kyu

Subjects
Physics - Chemical Physics, Condensed Matter - Other Condensed Matter
Abstract

Development of cost-effective hydrogen evolution reaction (HER) catalysts with outstanding catalytic activity, replacing cost-prohibitive noble metal-based catalysts, is critical for practical green hydrogen production. A popular strategy for promoting the catalytic performance of noble metal-free catalysts is to incorporate earth-abundant transition metal (TM) atoms into nanocarbon platforms such as carbon quantum dots (CQDs). Although data-driven catalyst design methods can significantly accelerate the rational design of TM element-doped CQD (M@CQD) catalysts, they suffer from either a simplified theoretical model or the prohibitive cost and complexity of experimental data generation. In this study, we propose an effective and facile HER catalyst design strategy based on machine learning (ML) and ML model verification using electrochemical methods accompanied with density functional theory (DFT) simulations. Based on a Bayesian genetic algorithm (BGA) ML model, the Ni@CQD catalyst on a three-dimensional reduced graphene oxide (3D rGO) conductor is proposed as the best HER catalyst under the optimal conditions of catalyst loading, electrode type, and temperature and pH of electrolyte. We validate the ML results with electrochemical experiments, where the Ni@CQD catalyst exhibited superior HER activity, requiring an overpotential of 189 mV to achieve 10 mA cm-2 with a Tafel slope of 52 mV dec-1 and impressive durability in acidic media. We expect that this methodology and the excellent performance of the Ni@CQD catalyst provide an effective route for the rational design of highly active electrocatalysts for commercial applications.

Published
2022

3. Zn-Ion Transporting, In Situ Formed Robust Solid Electrolyte Interphase for Stable Zinc Metal Anodes over a Wide Temperature Range

Author

Xiong, Peixun, Kang, Yingbo, Yao, Nan, Chen, Xiang, Mao, Haiyan, Jang, Woo-Sung, Halat, David M, Fu, Zhong-Heng, Jung, Min-Hyoung, Jeong, Hu Young, Kim, Young-Min, Reimer, Jeffrey A, Zhang, Qiang, and Park, Ho Seok

Subjects
Engineering, Materials Engineering, Chemical Sciences, Physical Chemistry, Affordable and Clean Energy, Chemical sciences
Abstract

Hydrogen evolution, corrosion, and dendrite formation in the Zn anodes limit their practical applications in aqueous Zn metal batteries. Herein, we propose an interfacial chemistry regulation strategy that uses hybrid electrolytes of water and a polar aprotic N,N-dimethylformamide to modify the Zn2+-solvation structure and in situ form a robust and Zn2+-conducting Zn5(CO3)2(OH)6 solid electrolyte interphase (SEI) on the Zn surface to achieve stable and dendrite-free Zn plating/stripping over a wide temperature range. As confirmed by 67Zn nuclear magnetic resonance relaxometry, electrochemical characterizations, and molecular dynamics simulation, the electrochemically and thermally stable Zn5(OH)6(CO3)2-contained SEI achieved a high ionic conductivity of 0.04 to 1.27 mS cm-1 from −30 to 70 °C and a thermally activated fast Zn2+ migration through the [010] plane. Consequently, extremely stable Zn-ion hybrid capacitors in hybrid electrolytes are demonstrated with high capacity retentions and Coulombic efficiencies over 14,000, 10,000, and 600 cycles at 25, −20, and 70 °C, respectively.

Published
2023

36. Self‐supported VO2 on polydopamine‐derived pyroprotein‐based fibers for ultrastable and flexible aqueous zinc‐ion batteries.

Author

Yeon, Jeong Seok, Park, Sul Ki, Kim, Shinik, Mohite, Santosh V., Il Kim, Won, Jang, Gun, Jang, Hyun‐Seok, Bae, Jiyoung, Lee, Sang Moon, Hong, Won G., Kim, Byung Hoon, Kim, Yeonho, and Park, Ho Seok

Subjects
ENERGY storage, ELECTRIC conductivity, SUBSTRATES (Materials science), OXYGEN consumption, STORAGE batteries, ZINC electrodes
Abstract

A conventional electrode composite for rechargeable zinc‐ion batteries (ZIBs) includes a binder for strong adhesion between the electrode material and the current collector. However, the introduction of a binder leads to electrochemical inactivity and low electrical conductivity, resulting in the decay of the capacity and a low rate capability. We present a binder‐ and conducting agent‐free VO2 composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein‐based fibers. The as‐fabricated composite electrode was used as a substrate for the direct growth of VO2 as a self‐supported form on polydopamine‐derived pyroprotein‐based fibers (pp‐fibers@VO2(B)). It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO2(B) cathode. In addition, their electrochemical mechanism was elucidated. Their energy storage is induced by Zn2+/H+ coinsertion during discharging, which can be confirmed by the lattice expansion, the formation of by‐products including Znx(OTf)y(OH)2x−y·nH2O, and the reduction of V4+ to V3+. Furthermore, the assembled Zn//pp‐fibers@VO2(B) pouch cells have excellent flexibility and stable electrochemical performance under various bending states, showing application possibilities for portable and wearable power sources. [ABSTRACT FROM AUTHOR]

Published
2024
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38. Trifunctional robust electrocatalysts based on 3D Fe/N‐doped carbon nanocubes encapsulating Co4N nanoparticles for efficient battery‐powered water electrolyzers

Author

Choi, Hyung Wook, primary, Lee, Hongdae, additional, Lu, Jun, additional, Bin Kwon, Seok, additional, Jeong, Dong In, additional, Park, Beum Jin, additional, Kim, Jiwon, additional, Kang, Bong Kyun, additional, Jang, Gun, additional, Yoon, Dae Ho, additional, and Park, Ho Seok, additional

Published
2024
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40. High Na‐ion conductivity and mechanical integrity of anion‐exchanged polymeric hydrogel electrolytes for flexible sodium ion hybrid energy storage

Author

Hong, Jung Woo, primary, Rana, Harpalsinh H., additional, Park, Jeong Hee, additional, Kim, Jun Su, additional, Lee, Sang Joon, additional, Jang, Gun, additional, Kang, Tae Hoon, additional, Shin, Kang Ho, additional, Baek, Sang Ha, additional, Yang, Wooseok, additional, Kim, Kwang Ho, additional, Lee, Ju‐Hyuk, additional, and Park, Ho Seok, additional

Published
2024
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43. Generic Synthesis of High Entropy Phosphides for Fast and Stable Li-Ion Storage

Author

Li, Wenwu, primary, Li, Yanhong, additional, Wang, Jeng-Han, additional, Huang, Shengchi, additional, Chen, Anjie, additional, Yang, Lufeng, additional, Chen, Jie, additional, He, Lunhua, additional, Pang, Wei Kong, additional, Thomsen, Lars, additional, Cowie, Bruce, additional, Xiong, Peixun, additional, Zhou, Yucun, additional, Gun, Jang, additional, Min, Dong Hyun, additional, Byun, Jin Suk, additional, Xu, Lei, additional, Huang, Jia-Qi, additional, Roh, Kwang Chul, additional, Kang, Seo Hui, additional, Liu, Meilin, additional, Duan, Xiangfeng, additional, and Park, Ho Seok, additional

Published
2024
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50. Interfacial Design of Ti3C2Tx MXene/Graphene Heterostructures Boosted Ru Nanoclusters with High Activity Toward Hydrogen Evolution Reaction.

Author

Yu, Xu, Li, Yong, Pei, Chengang, Lu, Yanhui, Kim, Jung Kyu, Park, Ho Seok, and Pang, Huan

Subjects
HYDROGEN evolution reactions, GRAPHENE, HYDROGEN production, HETEROSTRUCTURES, DENSITY functional theory, GRAPHENE oxide
Abstract

The development of a cost‐competitive and efficient electrocatalyst is both attractive and challenging for hydrogen production by hydrogen evolution reaction (HER). Herein, a facile glycol reduction method to construct Ru nanoclusters coupled with hierarchical exfoliated‐MXene/reduced graphene oxide architectures (Ru‐E‐MXene/rGA) is reported. The hierarchical structure, formed by the self‐assembly of graphene oxides, can effectively prohibit the self‐stacking of MXene nanosheets. Meanwhile, the formation of the MXene/rGA interface can strongly trap the Ru3+ ions, resulting in the uniform distribution of Ru nanoclusters within Ru‐E‐MXene/rGA. The boosted catalytic activity and underlying catalytic mechanism during the HER process are proved by density functional theory. Ru‐E‐MXene/rGA exhibits overpotentials of 42 and 62 mV at 10 mA cm−2 in alkaline and acidic electrolytes, respectively. The small Tafel slope and charge transfer resistance (Rct) values elucidate its fast dynamic behavior. The cyclic voltammetry (CV) curves and chronoamperometry test confirm the high stability of Ru‐E‐MXene/rGA. These results demonstrate that coupling Ru nanoclusters with the MXene/rGA heterostructure represents an efficient strategy for constructing MXene‐based catalysts with enhanced HER activity. [ABSTRACT FROM AUTHOR]

Published
2024
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