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Luo X, Zhou Q, Du S, Li J, Zhong J, Deng X, Liu Y. Porous Co 9S 8/Nitrogen, Sulfur-Doped Carbon@Mo 2C Dual Catalyst for Efficient Water Splitting. ACS APPLIED MATERIALS & INTERFACES 2018; 10:22291-22302. [PMID: 29882412 DOI: 10.1021/acsami.8b06166] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The exploration of highly efficient and stable bifunctional electrocatalysts for overall water splitting is currently of extreme interest for the efficient conversion of sustainable energy sources. Herein, we provide an earth-abundant, low-cost, and highly efficient bifunctional electrocatalyst composed of cobalt sulfide (Co9S8) and molybdenum carbide (Mo2C) nanoparticles anchored to metal-organic frameworks (MOFs)-derived nitrogen, sulfur-codoped graphitic carbon (Co9S8-NSC@Mo2C). The new composite mode of the electrocatalyst was realized through simple pyrolysis processes. The composite electrocatalyst shows outstanding hydrogen evolution reaction (HER) performance and excellent stability over the entire pH range. For example, it has a lower overpotential of 74, 89, and 121 mV with the Tafel slopes of 69.3, 86.7, and 106.4 mV dec-1 to achieve a current density of 10 mA cm-2 in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M phosphate-buffered saline solutions, respectively. Moreover, it shows a small overpotential of 293 mV with a Tafel slope of 59.7 mV dec-1 to reach 10 mA cm-2 for the oxygen evolution reaction (OER) in 1.0 M KOH. The significantly enhanced HER and OER activities of Co9S8-NSC@Mo2C are mainly attributable to the electron transfer from Co to Mo2C, resulting in a lower Mo valence and a higher Co valence in Co9S8-NSC@Mo2C. Furthermore, using the Co9S8-NSC@Mo2C bifunctional electrocatalyst as both the anode for the OER and the cathode for the HER for overall water splitting, a cell voltage of only 1.61 V is needed to derive a current density of 10 mA cm-2. This interesting work offers a general method for designing and fabricating highly efficient and stable non-noble electrocatalysts for promising energy conversion.
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Affiliation(s)
- Xiaohu Luo
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
- School of Chemistry and Chemical Engineering , Qiannan Normal University for Nationalities , Duyun , Guizhou 558000 , P. R. China
| | - Qiulan Zhou
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
| | - Shuo Du
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
| | - Ji Li
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
| | - Jiawen Zhong
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
| | - Xiulin Deng
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
| | - Yali Liu
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering , Hunan University , Changsha , Hunan 410082 , P. R. China
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Luo Y, Li X, Cai X, Zou X, Kang F, Cheng HM, Liu B. Two-Dimensional MoS 2 Confined Co(OH) 2 Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes. ACS NANO 2018; 12:4565-4573. [PMID: 29688695 DOI: 10.1021/acsnano.8b00942] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The development of abundant and cheap electrocatalysts for the hydrogen evolution reaction (HER) has attracted increasing attention over recent years. However, to achieve low-cost HER electrocatalysis, especially in alkaline media, is still a big challenge due to the sluggish water dissociation kinetics as well as the poor long-term stability of catalysts. In this paper we report the design and synthesis of a two-dimensional (2D) MoS2 confined Co(OH)2 nanoparticle electrocatalyst, which accelerates water dissociation and exhibits good durability in alkaline solutions, leading to significant improvement in HER performance. A two-step method was used to synthesize the electrocatalyst, starting with the lithium intercalation of exfoliated MoS2 nanosheets followed by Co2+ exchange in alkaline media to form MoS2 intercalated with Co(OH)2 nanoparticles (denoted Co-Ex-MoS2), which was fully characterized by spectroscopic studies. Electrochemical tests indicated that the electrocatalyst exhibits superior HER activity and excellent stability, with an onset overpotential and Tafel slope as low as 15 mV and 53 mV dec-1, respectively, which are among the best values reported so far for the Pt-free HER in alkaline media. Furthermore, density functional theory calculations show that the cojoint roles of Co(OH)2 nanoparticles and MoS2 nanosheets result in the excellent activity of the Co-Ex-MoS2 electrocatalyst, and the good stability is attributed to the confinement of the Co(OH)2 nanoparticles. This work provides an imporant strategy for designing HER electrocatalysts in alkaline solutions, and can, in principle, be expanded to other materials besides the Co(OH)2 and MoS2 used here.
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Affiliation(s)
- Yuting Luo
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
| | - Xu Li
- Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , PR China
| | - Xingke Cai
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
| | - Xiaolong Zou
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
| | - Feiyu Kang
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
- Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , PR China
| | - Hui-Ming Cheng
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
- Shenyang National Laboratory for Materials Science, Institute of Metal Research , Chinese Academy of Sciences , Shenyang , Liaoning 110016 , PR China
| | - Bilu Liu
- Shenzhen Geim Graphene Center (SGC), Tsinghua-Berkeley Shenzhen Institute (TBSI) , Tsinghua University , Shenzhen 518055 , PR China
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