Oxygen evolution reaction (OER) is a crucial half-reaction for many energy conversion technologies, which requires efficient catalysts to boost its sluggish kinetics. Herein, the FeNi catalyst with a high phosphating level (HP-FexNi2−xP) is constructed by a three-step synthetic route: (i) hydrothermal deposition of lamellar sheets, (ii) NaBH4 pretreatment, and (iii) in situ phosphorization. FeNi layered double lamellar hydroxides were synthesized as the pre-catalysts. Then NaBH4 pretreatment was used to remove the oxide impurities and introduce oxygen vacancies to promote phosphorization in the subsequent process. Finally, HP-FexNi2−xP nanosheets were achieved, with several advantages like abundant exposed active sites, high conductivity, and accessible mass transport channels. During the OER process, FeNiOOH/HP-FexNi2−xP interfaces are formed through spontaneous electrochemical activation and surface reconstruction. Benefitting from the synergistic interfacial effect and abundant exposed active sites, the NiFe based catalysts show an overpotential of ≈ 208 mV to reach 10 mA cm−2 in 1 M KOH, and a stability of 200 h at 1 A cm−2. Overall, this work reports the rational design and preparation of a highly active OER catalyst, but also provides a general route through NaBH4 pretreatment, which can be usefully applied to promote phosphorization in other systems of interest for catalytic applications.
Boron pretreatment promotes phosphorization of FeNi catalysts for oxygen evolution
Vomiero A.;
2023-01-01
Abstract
Oxygen evolution reaction (OER) is a crucial half-reaction for many energy conversion technologies, which requires efficient catalysts to boost its sluggish kinetics. Herein, the FeNi catalyst with a high phosphating level (HP-FexNi2−xP) is constructed by a three-step synthetic route: (i) hydrothermal deposition of lamellar sheets, (ii) NaBH4 pretreatment, and (iii) in situ phosphorization. FeNi layered double lamellar hydroxides were synthesized as the pre-catalysts. Then NaBH4 pretreatment was used to remove the oxide impurities and introduce oxygen vacancies to promote phosphorization in the subsequent process. Finally, HP-FexNi2−xP nanosheets were achieved, with several advantages like abundant exposed active sites, high conductivity, and accessible mass transport channels. During the OER process, FeNiOOH/HP-FexNi2−xP interfaces are formed through spontaneous electrochemical activation and surface reconstruction. Benefitting from the synergistic interfacial effect and abundant exposed active sites, the NiFe based catalysts show an overpotential of ≈ 208 mV to reach 10 mA cm−2 in 1 M KOH, and a stability of 200 h at 1 A cm−2. Overall, this work reports the rational design and preparation of a highly active OER catalyst, but also provides a general route through NaBH4 pretreatment, which can be usefully applied to promote phosphorization in other systems of interest for catalytic applications.
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