Overall Water Splitting with Room-Temperature Synthesized NiFe Oxyfluoride Nanoporous Films

Abstract

A room-temperature synthesis of NiFe oxyfluoride (NiFeOF) holey film, using electrochemical deposition and anodic treatments, has been developed in this work. The developed room-temperature synthetic route can preserve the fine nanoporous structure inside the holey film, providing high surface area and abundant reaction sites for electrocatalytic reactions. Both computational and experimental studies demonstrate that the developed NiFeOF holey film with highly porous structure and metal residuals can be used as a high-efficiency and bifunctional catalyst for overall water splitting. Simulation result indicates that the exposed Ni atom on the NiFeOF surface serves as the active site for water splitting. Fe doping can improve the catalytic activity of the Ni active site due to the partial charge-transfer effect of Fe3+ on Ni2+. Electrochemical performance of the NiFeOF catalyst can be experimentally further enhanced through improved electrical conductivity by the residual NiFe alloy framework inside the holey film. The synergistic combination of NiFeOF holey film properties results in a highly efficient electrochemical catalyst, showing overall water splitting.

Investigation of mixed-metal (oxy)fluorides as a new class of water oxidation electrocatalysts

“…25,26 Even if the advantages of the introduction of uorine element in changing the chemical properties and electronic structures have been demonstrated, 27 only rare reports were found in the literature on uorides or oxyuorides as efficient catalyst for water oxidation. [28][29][30][31][32][33] The lack of studies could be explained by the challenging task to prepare oxyuorides due to the difficulty to stabilize both uorine and oxygen anions despite their similar ionic radii (F 1.31Å, O 1.38Å). Indeed, the number of ironbased oxyuoride synthetic methods remains modest in the literature compared to pure oxides and uorides.…”

Hollow Nanocages of NixCo1−xSe for Efficient Zinc–Air Batteries and Overall Water Splitting

“…The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are the key reversible reactions occurring at the cathode of ZABs and largely determine the energy-conversion efficiency of ZABs [4]. The OER and the hydrogen evolution reaction (HER) are the two electrochemical reactions for catalyzing overall water splitting [5][6][7]. Pt-based materials have been widely considered as state-of-the-art electrocatalysts for the ORR and HER [8][9][10][11][12], while RuO 2 and IrO 2 are the standard high-efficiency OER catalysts [13,14].…”

Investigation of Amorphous Mixed-Metal (Oxy)Fluorides as a New Class of Water Oxidation Electrocatalysts

“…19,20 Even if the advantages of the introduction of fluorine element in changing the chemical properties and electronic structures have been demonstrated, 21 only rare reports were found in the literature on fluorides or oxyfluorides as efficient catalyst for water oxidation. [22][23][24][25][26][27] The lack of studies could be explained by the challenging task to prepare oxyfluorides due to the difficulty to stabilize both fluorine and oxygen anions despite their similar ionic radii (F 1.31 Å, O 1.38 Å). Indeed, the number of iron-based oxyfluoride synthetic methods remains modest in the literature compared to pure oxides and fluorides.…”