Boosting the oxygen evolution electrocatalysis of high-entropy hydroxides by high-valence nickel species regulation

Abstract

An amorphous NiCoFeCrMo-based high-entropy hydroxide possesses the maximum content of high-valence Ni3+ species, boosting the oxygen evolution electrocatalytic performance.

Strengthening the Stability of the Reconstructed NiOOH Phase for 5-Hydroxymethylfurfural Oxidation

“…According to Figure S1a, four weak diffraction peaks at 28.5, 33.0, 45.9, and 56.3° correspond to the (111), (200), (220), and (311) planes of cubic CeO 2 (JCPDS 34-0394), respectively . In Figure S1b, three diffraction peaks at 23.3, 34.3, and 60.6° are well matched with the (101), (015), and (110) planes of Ni­(OH) 2 (JCPDS 38-0715) . When the Ce species was added into the prepared sample, several broad and weak diffraction peaks are observed (22.6, 33.2, and 59.6°), which could be classified as the phase of Ni­(OH) 2 ; no obvious diffraction peaks of CeO 2 appeared in 14%Ce-Ni­(OH) 2 , demonstrating that Ce was implanted as the dopant atom.…”

“…49 When the potential exceeds 0.6 V vs Ag/AgCl, the linearly increased current is attributed to the superposition of HMF oxidation and OER rather than the separate OER. 22 Obviously, the initial potential of HMF oxidation is smaller than that of the OER, which demonstrates that HMF oxidation is prior to the OER. The Tafel slope of HMF oxidation is lower than that of the OER, which also reveals that HMF oxidation has favorable reaction kinetics (Figure S8).…”

Engineering cation vacancies in high-entropy layered double hydroxides for boosting the oxygen evolution reaction

“…5 Among the HEM family, high-entropy layered double hydroxides (HE-LDHs) stand out because of their excellent performance in the field of OER catalysis. 6,7 However, the relevant research has focused on the development of HE-LDH electrode materials with a high OER catalytic activity, although little has been revealed on how to improve the catalytic stability.…”

Surface valence regulation of cobalt–nickel foams for glucose oxidation-assisted water electrolysis

“…13,14 More importantly, the energetic oxidizing ability also increases the amount of high-valence transition metal species, which are recognized as the active species for water oxidation. 11,15 Herein, taking Co-Ni foam (CNF) as a model electrocatalyst, we report an ultrafast O 2 plasma treatment (within 5 min) towards surface-controlled CNF for glucose oxidation-assisted water electrolysis. Since the electrocatalytic reactions usually occur at the electrocatalysts' surface and the high-valence metal species are mainly responsible for the electrooxidation reaction, 16,17 the O 2 plasma treatment endows the CNF with abundant Co 3+ , a superhydrophilic surface, an enlarged electrochemical surface area, a strong response towards glucose molecules and fast charge transport kinetics, thereby enhancing the electrocatalytic performance of glucose electro-oxidation coupled with hydrogen production.…”

“…13,14 More importantly, the energetic oxidizing ability also increases the amount of high-valence transition metal species, which are recognized as the active species for water oxidation. 11,15…”