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Open Access Research Article Issue
Honeycomb-like MXene/NiFePx–NC with "continuous" single-crystal enabling high activity and robust durability in electrocatalytic oxygen evolution reactions
Journal of Advanced Ceramics 2023, 12 (3): 553-564
Published: 16 February 2023
Downloads:382

The development of low-cost, stable, and robust non-noble metal catalysts for water oxidation is a pivotal challenge for sustainable hydrogen production through electrocatalytic water splitting. Currently, such catalysts suffer from high overpotential and sluggish kinetics in oxygen evolution reactions (OERs). Herein, we report a "continuous" single-crystal honeycomb-like MXene/NiFePx–N-doped carbon (NC) heterostructure, in which ultrasmall NiFePx nanoparticles (NPs) encapsulated in the NC are tightly anchored on a layered MXene. Interestingly, this MXene/NiFePx–NC delivers outstanding OER catalytic performance, which stems from "continuous" single-crystal characteristics, abundant active sites derived from the ultrasmall NiFePx NPs, and the stable honeycomb-like heterostructure with an open structure. The experimental results are rationalized theoretically (by density functional theory (DFT) calculations), which suggests that it is the unique MXene/NiFePx–NC heterostructure that promotes the sluggish OER, thereby enabling superior durability and excellent activity with an ultralow overpotential of 240 mV at a current density of 10 mA·cm−2.

Open Access Research Article Issue
Coupling of ultrasmall and small CoxP nanoparticles confined in porous SiO2 matrix for a robust oxygen evolution reaction
Nano Materials Science 2022, 4 (4): 393-399
Published: 14 April 2022
Downloads:2

Rational design of electrocatalysts is important for a sustainable oxygen evolution reaction (OER). It is still a huge challenge to engineer active sites in multi-sizes and multi-components simultaneously. Here, a series of CoP nanoparticles (NPs) confined in an SiO2 matrix (SiO2/CoxP) is designed and synthesized as OER electrocatalysts. The phosphorization of the hydrolyzed Co-phyllosilicate promotes the formation of ultrasmall and small Co2P and CoP. These are firmly confined in the SiO2 matrix. The coupling of multi-size and multi-component CoP catalysts can regulate reaction kinetics and electron transfer ability, enrich the active sites, and eventually promote the intrinsic OER activity. The SiO2 matrix provides abundant porous structure and oxygen vacancies, and these facilitate the exposure of active sites and improve conductivity. Because of the synergy and interplay of multi-sized/component CoxP NPs and the porous SiO2 matrix, the unique SiO2/CoP heterostructure exhibits low overpotential (293 ​mV@10 ​mA ​cm-2), and robust stability (decay 12 ​mV after 5000 CV cycles, 97.4% of initial current after 100 ​h chronoamperometric) for the OER process, exceeding many advanced metal phosphide electrocatalysts. This work provides a novel tactic to design low-cost, simple, and highly efficient OER electrocatalysts.

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