(560bb) 3D Nitrogen-Doped Graphene Aerogel-Supported MnO Nanoparticles As Efficient Electrocatalyst for CO2 Conversion to CO

3D Nitrogen-Doped Graphene Aerogel-Supported MnO
Nanoparticles as Efficient Electrocatalyst for CO₂ Conversion to CO

Bike
Zhang, Mengchu Wang, Yi He, Yao Shi

Institute of Industrial
Ecology and Environment, College of Chemical and Biological Engineering,
Zhejiang University, Hangzhou 310027, China

Abstract:Electrochemical
CO₂ reduction reaction (CO₂RR) is a promising option for
converting CO₂ waste streams into useful chemicals, which has
attracted wide attention. The viability of this process, however, is still
facing several crucial limitations such as the prohibitively high electrochemical
overpotential and poor product selectivity due to the competitive process of
the hydrogen evolution reaction (HER). Herein, for the first time
three-dimensional (3D) N-doped graphene aerogel (NGA) support MnO nanoparticles
(MnO/NGA) as efficient CO₂RR catalyst synthesized via a facile and
scalable hydrogel route is applied for the CO₂RR. This novel catalyst exhibits an extremely low overpotential of 0.16 V (vs RHE), high Faradaic efficiency of
86% for CO at potential of −0.82 V (vs RHE), which is much better than most
of reported Mn-based materials to our knowledge with a current density of 7.6
mA cm⁻², as well as good long-term stability. The unique 3D crumpled
porous nanostructure of NGA with large specific area facilitate reactant
diffusion in pores, maximize the electrode/electrolyte contact area and promote
electron transport. Well crystallized MnO nanoparticles are believed to be the
metallic sites active sites towards CO₂, which have a clear positive
correlation with the catalyst activity. Evidence is provided by the significant
differences of CO₂ electrocatalytic performance between MnO/NGA-2 (MnO
with good crystallinity) and MnO/NGA-1 (Mn in ionic chemical state). In
addition, doped nitrogen can effectively suppress the HER. Our results highlight
on a promising new class of low-cost, abundant electrocatalysts for CO₂RR.

Key words: MnO, 3D N-doped graphene aerogel, electrocatalysts, CO₂ reduction

Fig.1. Faradaic efficiency (FE) over MnO/NGA catalysts.
The data were obtained by chronoamperometry (CA) for 1 h, in 0.5 M KHCO₃
saturated with CO₂ (pH=7.2) at room temperature.