Nitrogen-Doped Carbon-Encased Bimetallic Selenide for High-Performance Water Electrolysis

Abstract

Highlights

N-Doped carbon-encased bimetallic selenide hybrid with strong synergistic effect is constructed.

N-Doped carbon-encased bimetallic selenide hybrid exhibits an excellent catalytic activity and stability for oxygen evolution reaction (OER) in alkaline media.

The superior OER activity is attributed to the highly active Co–OOH species and modified electron transfer process from Ni atoms.

Alternate abstract:

Demand of highly efficient earth-abundant transition metal-based electrocatalysts to replace noble metal materials for boosting oxygen evolution reaction (OER) is rapidly growing. Herein, an electrochemically exfoliated graphite (EG) foil supported bimetallic selenide encased in N-doped carbon (EG/(Co, Ni)Se₂–NC) hybrid is developed and synthesized by a vapor-phase hydrothermal strategy and subsequent selenization process. The as-prepared EG/(Co, Ni)Se₂–NC hybrid exhibits a core–shell structure where the particle diameter of (Co, Ni)Se₂ core is about 70 nm and the thickness of N-doped carbon shell is approximately 5 nm. Benefitting from the synergistic effects between the combination of highly active Co species and improved electron transfer from Ni species, and N-doped carbon, the EG/(Co, Ni)Se₂–NC hybrid shows remarkable electrocatalytic activity toward OER with a comparatively low overpotential of 258 mV at an current density of 10 mA cm⁻² and a small Tafel slope of 73.3 mV dec⁻¹. The excellent OER catalysis performance of EG/(Co, Ni)Se₂–NC hybrid is much better than that of commercial Ir/C (343 mV at 10 mA cm⁻² and 98.1 mV dec⁻¹), and even almost the best among all previously reported binary CoNi selenide-based OER electrocatalysts. Furthermore, in situ electrochemical Raman spectroscopy combined with ex situ X-ray photoelectron spectroscopy analysis indicates that the superb OER catalysis activity can be attributed to the highly active Co–OOH species and modified electron transfer process from Ni element.