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Nguyen CT, Luu TA, Nguyen TD, Dam AT, Le LT, Han H, Lo ST, Phan PT, Pham HT, Nguyen HNT, Nguyen LL, Nguyen HQ, Tran PD. Exploring the Sub-nanoscale Structure of Cobalt Molybdenum Sulfide and the Role of a Cobalt Promoter in Catalytic Hydrogen Evolution. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 36913544 DOI: 10.1021/acsami.2c20237] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Cobalt-promoted molybdenum sulfide (CoMoS) is known as a promising catalyst for H2 evolution reaction and hydrogen desulfurization reaction. This material exhibits superior catalytic activity as compared to its pristine molybdenum sulfide counterpart. However, revealing the actual structure of cobalt-promoted molybdenum sulfide as well as the plausible contribution of a cobalt promoter is still challenging, especially when the material has an amorphous nature. Herein, we report, for the first time, on the use of positron annihilation spectroscopy (PAS), being a nondestructive nuclear radiation-based method, to visualize the position of a Co promoter within the structure of MoS at the atomic scale, which is inaccessible by conventional characterization tools. It is found that at low concentrations, a Co atom occupies preferably the Mo-vacancies, thus generating the ternary phase CoMoS whose structure is composed of a Co-S-Mo building block. Increasing the Co concentration, e.g., a Co/Mo molar ratio of higher than 1.12/1, leads to the occupation of both Mo-vacancies and S-vacancies by Co. In this case, secondary phases such as MoS and CoS are also produced together with the CoMoS one. Combining the PAS and electrochemical analyses, we highlight the important contribution of a Co promoter to enhancing the catalytic H2 evolution activity. Having more Co promoter in the Mo-vacancies promotes the H2 evolution rate, whereas having Co in the S-vacancies causes a drop in H2 evolution ability. Furthermore, the occupation of Co to the S-vacancies leads also to the destabilization of the CoMoS catalyst, resulting in a rapid degradation of catalytic activity.
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Affiliation(s)
- Chuc T Nguyen
- Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
| | - Tuyen Anh Luu
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
- Dzhelepov Laboratory of Nuclear Problems, JINR, 141980 Dubna, Moscow Region, Russia
| | - Thai D Nguyen
- Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
| | - An T Dam
- Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
| | - Ly T Le
- Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
| | - Hyuksu Han
- Department of Energy Engineering, Konkuk University, 120 Neungdong-ro Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Son T Lo
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
| | - Phuc T Phan
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
| | - Hue T Pham
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
| | - Hue N T Nguyen
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
| | - La Ly Nguyen
- Center for Nuclear Technologies, Vietnam Atomic Energy Institute, 217 Nguyen Trai, Ho Chi Minh City 700000, Vietnam
| | - Hung Q Nguyen
- Institute of Fundamental and Applied Sciences, Duy Tan University, 6 Tran Nhat Duat, Ho Chi Minh City 700000, Vietnam
- Faculty of Natural Sciences, Duy Tan University, 3 Quang Trung, Da Nang City 550000, Vietnam
| | - Phong D Tran
- Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
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Tuyen L, Dong Xuan T, Tuan Kiet H, Chi Cuong L, Trong Phuc P, Duy Tap T, Phuc DV, Nguyen L, Ngoc Hue N, Thi Hue P, Thai Son L, Van Hoang D, Hoang Long N, Quang Hung N. A hybrid model for estimation of pore size from ortho-positronium lifetimes in porous materials. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.108867] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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