Manifestation of Concealed Defects in MoS2 Nanospheres for Efficient and Durable Electrocatalytic Hydrogen Evolution Reaction. Issue 17 (13th June 2017)

• Record Type: Journal Article
• Authors: Senthil Kumar, Sakkarapalayam Murugesan; Selvakumar, Karuppiah; Karthikeyan, Jeyakumar; Thangamuthu, Rangasamy; Murugan, Palanichamy; Rajput, Parasmani; Jha, Shambhu Nath; Bhattacharyya, Dibyendu; Navascues, Nuria; Irusta., Silvia
• Is Part Of: ChemistrySelect. Volume 2:Issue 17(2017)
• Page Start: 4667
• Page End: 4672
• Publication Date: 2017-06-13
• Subjects: Concealed defects -- curved surface -- HER activity -- MoS2 nanospheres -- point defects; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201700103
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: MoS2 nanospheres were formed using a template free hydrothermal process, which exhibit high catalytic activity towards hydrogen evolution reaction (HER). The extend of defect sites are probed by extended X‐ray absorption fine structure which found decrease in co‐ordination number at Mo site rather than at S site. DFT calculations identified an uneven strain and defect distribution between two S planes of curved MoS2 . Based on hydrogen adsorption on various sites, we identify a new pathway called "extended activity @ shielded defects", for Volmer‐Tafel and Volmer‐Heyrovsky mechanisms, where H adsorption occurs at exposed S layer driven by defects in underneath S layer of nanosphere. Having higher defect concentration it exhibited excellent HER activity with overpotential of −0.12 V, Tafel slope of 90 mV/decade, and higher turnover frequency. Our findings provide an avenue to design and engineer advanced nanostructures for catalysis, electronic devices, and other potential applications. Abstract : Cross‐section view of a MoS2 nanosphere is shown along with the adsorption energy of H and desorption energy of H2 on different types of active sites. Concealed S defect site shows an optimum adsorption energy and less desorption energy. While the direct S point defect site shows high adsorption as well as desorption energy. This show that the turn over frequency (TOF) will be less for the activity on direct S defect, which is in agreement with our experimental observations.