A Heterostructure Coupling of Exfoliated Ni–Fe Hydroxide Nanosheet and Defective Graphene as a Bifunctional Electrocatalyst for Overall Water Splitting. Issue 17 (3rd March 2017)

• Record Type: Journal Article
• Authors: Jia, Yi; Zhang, Longzhou; Gao, Guoping; Chen, Hua; Wang, Bei; Zhou, Jizhi; Soo, Mun Teng; Hong, Min; Yan, Xuecheng; Qian, Guangren; Zou, Jin; Du, Aijun; Yao, Xiangdong
• Is Part Of: Advanced materials. Volume 29:Issue 17(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-03-03
• Subjects: defects -- graphene -- heteroassembly -- layered double hydroxide -- nonprecious electrocatalysts; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201700017
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract : Herein, the authors demonstrate a heterostructured NiFe LDH‐NS@DG10 hybrid catalyst by coupling of exfoliated Ni–Fe layered double hydroxide (LDH) nanosheet (NS) and defective graphene (DG). The catalyst has exhibited extremely high electrocatalytic activity for oxygen evolution reaction (OER) in an alkaline solution with an overpotential of 0.21 V at a current density of 10 mA cm −2, which is comparable to the current record (≈0.20 V in Fe–Co–Ni metal‐oxide‐film system) and superior to all other non‐noble metal catalysts. Also, it possesses outstanding kinetics (Tafel slope of 52 mV dec −1 ) for the reaction. Interestingly, the NiFe LDH‐NS@DG10 hybrid has also exhibited the high hydrogen evolution reaction (HER) performance in an alkaline solution (with an overpotential of 115 mV by 2 mg cm −2 loading at a current density of 20 mA cm −2 ) in contrast to barely HER activity for NiFe LDH‐NS itself. As a result, the bifunctional catalyst the authors developed can achieve a current density of 20 mA cm −2 by a voltage of only 1.5 V, which is also a record for the overall water splitting. Density functional theory calculation reveals that the synergetic effects of highly exposed 3d transition metal atoms and carbon defects are essential for the bifunctional activity for OER and HER. Abstract : A heterostructure coupling of exfoliated Ni–Fe hydroxide nanosheet and defective graphene has been demonstrated, both experimentally and theoretically, to be active for electrocatalytic overall water splitting. Density functional theory calculations further reveal that the formed heterostrucutre can efficiently enhance the charge separation and redistribution, thus facilitating the hydrogen evolution reaction and oxygen evolution reaction conducted on defective graphene and NiFe layered double hydroxide nanosheet, respectively.