Design of Porous Core–Shell Manganese Oxides to Boost Electrocatalytic Dinitrogen Reduction
Yunnan Gao, Qineng Xia, Leiduan Hao, Alex W. Robertson, Zhenyu Sun
Abstract
Harnessing the electrochemical nitrogen reduction reaction (NRR), where renewable electricity and H2O are used for NH3 production, is regarded as an effective and clean protocol for N2 fixation. The design and development of new active, selective, and durable NRR electrocatalysts are expected to achieve this. Here, we design a well-defined porous core–shell heterostructure comprising Mn2O3–MnO (as the core) and Mn3O4 (as the shell). The unique composite is shown to efficiently facilitate N2 adsorption and reduction in a neutral electrolyte, delivering an impressive NH3 FE (∼23.8%) with a reasonable NH3 formation rate (22.4 μgNH3 h–1 mgcat–1) at a cathodic voltage of −0.3 V (versus reversible hydrogen electrode). The electrocatalytic properties can be readily modulated by tuning the shell thickness. Our measured performance surpasses those of most nonmetallic, transition-metal-, and noble-metal-based catalysts reported in the prior literature. Equally importantly, the electrocatalytic activity maintains good stability up to 60 h. The outstanding electrochemical performance is attributed to the combined advantages of a large interface between the metal oxides and a unique core–shell structure with a high density of surface-exposed sites, pores, and oxygen vacancies.