Amorphous Nickel–Iron Borophosphate for a Robust and Efficient Oxygen Evolution Reaction. Issue 25 (16th May 2021)

• Record Type: Journal Article
• Authors: Kwon, Jiseok; Han, Hyuksu; Jo, Seonghan; Choi, Seunggun; Chung, Kyung Yoon; Ali, Ghulam; Park, Keemin; Paik, Ungyu; Song, Taeseup
• Is Part Of: Advanced energy materials. Volume 11:Issue 25(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-05-16
• Subjects: amorphous -- borophosphate -- oxygen evolution reaction -- structural flexibility -- water splitting; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202100624
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Borophosphate materials are promising electrocatalysts for water splitting. Their structural flexibility enable self‐adjusting of electronic structure depending on potential. The rich chemistry of borophosphate provides a huge engineering space to tune composition and structure. Herein, amorphized LiNiFe borophosphate (a‐LNFBPO) for an efficient and durable oxygen evolution reaction (OER) is first reported. Facile adsorption of oxygen intermediates on the vacancies generated by spontaneous Li dissolution during the OER and regulated electronic structure resulting from the Ni and Fe interaction can boost the OER. The amorphization of LiNiFe borophosphate modifies the electronic structure with metal‐oxygen (MO) bond contraction and the high valence state of the metal cations, which reduces the charge transfer energy between the catalyst and electrolyte. In addition, abundant defects, dangling bonds, and a disordered arrangement induced by amorphization enable an improvement in structural flexibility, facilitating a facile and entire transformation of originally inert species into the active phase during the OER process. The a‐LNFBPO@Ni foam shows excellent OER properties requiring only a 215 mV overpotential for generating 10 mA cm −2 and long‐term stability over 300 h. Abstract : Amorphization of LiNiFe borophosphate induces defects, dangling bonds, and a disordered arrangement with an increased valence state of metal cations and contraction of the metal‐oxygen (MO) bonds in [MO]6 octahedrons, endowing strong MO covalency and enhanced structural flexibility. These features enable facile and entire transformation of originally inert species into a catalytic active phase during the oxygen evolution reaction (OER), boosting OER performance.