Bimetallic Nickel‐Substituted Cobalt‐Borate Nanowire Array: An Earth‐Abundant Water Oxidation Electrocatalyst with Superior Activity and Durability at Near Neutral pH. Issue 25 (16th May 2017)

• Record Type: Journal Article
• Authors: Ma, Min; Qu, Fengli; Ji, Xuqiang; Liu, Danni; Hao, Shuai; Du, Gu; Asiri, Abdullah M.; Yao, Yadong; Chen, Liang; Sun, Xuping
• Is Part Of: Small. Volume 13:Issue 25(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-05-16
• Subjects: Ni‐Co‐Bi nanowire arrays -- oxidative polarization -- water oxidation catalysts; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201700394
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract : There is an urgent demand to develop earth‐abundant electrocatalysts for efficient and durable water oxidation under mild conditions. A nickel‐substituted cobalt‐borate nanowire array is developed on carbon cloth (Ni‐Co‐Bi/CC) via oxidative polarization of NiCo2 S4 nanoarray in potassium borate (K‐Bi). As a bimetallic electrocatalyst for water oxidation, such Ni‐Co‐Bi/CC is superior in catalytic activity and durability in 0.1m K‐Bi (pH: 9.2), with a turnover frequency of 0.33 mol O2 s −1 at the overpotential of 500 mV and nearly 100% Faradaic efficiency. To drive a geometrical catalytic current density of 10 mA cm −2, it only needs overpotential of 388 mV, 34 mV less than that for Co‐Bi/CC, outperforming reported non‐noble‐metal catalysts operating under benign conditions. Notably, its activity is maintained over 80 000 s. Density functional theory calculations suggest that the O* to OOH* conversion is the rate‐determining step and Ni substitution decreases the free energy on Co‐Bi from 2.092 to 1.986 eV. Abstract : Nickel‐substituted cobalt‐borate nanowire array on carbon cloth (Ni‐Co‐Bi/CC) shows superior water oxidation activity and durability in 0.1m K‐Bi. To drive 10 mA cm −2, Ni‐Co‐Bi/CC only needs an overpotential of 388 mV, 34 mV less than that for Co‐Bi/CC. The activity enhancement for Co‐Bi after Ni substitution can be attributed to the decreased free energy for the O* to OOH* conversion.