Work

Optimizing the Lattice Nitrogen Coordination to Break the Performance Limitation of Metal Nitrides for Electrocatalytic Nitrogen Reduction

Year: 2024

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Metal nitrides (MNs) are attracting enormous attention in the electrocatalytic nitrogen reduction reaction (NRR) because of their rich lattice nitrogen (N lat ) and the unique ability of N lat vacancies to activate N 2 . However, continuing controversy exists on whether MNs are catalytically active for NRR or produce NH 3 via the reductive decomposition of N lat without N 2 activation in the in situ electrochemical conditions, let alone the rational design of high-performance MN catalysts. Herein, we focus on the common rocksalt-type MN(100) catalysts and establish a quantitative theoretical framework based on the first-principles microkinetic simulations to resolve these puzzles. The results show that the Mars-van Krevelen mechanism is kinetically more favorable to drive the NRR on a majority of MNs, in which N lat plays a pivotal role in achieving the Volmer process and N 2 activation. In terms of stability, activity, and selectivity, we find that MN(100) with moderate formation energy of N lat vacancy ( E vac ) can achieve maximum activity and maintain electrochemical stability, while low- or high- E vac ones are either unstable or catalytically less active. Unfortunately, owing to the five-coordinate structural feature of N lat on rocksalt-type MN(100), this maximum activity is limited to a yield of NH 3 of only ∼10 –15 mol s –1 cm –2 . Intriguingly, we identify a volcano-type activity-regulating role of the local structural features of N lat and show that the four-coordinate N lat can exhibit optimal activity and overcome the performance limitation, while less coordinated N lat fails. This work provides, arguably for the first time, an in-depth theoretical insight into the activity and stability paradox of MNs for NRR and underlines the importance of reaction kinetic assessment in comparison with the prevailing simple thermodynamic analysis.

Source: JACS Au

DOI: 10.1021/jacsau.4c00377

Authors: Haiyang Yuan, Chen Zhu, Yu Hou, Hua Gui Yang, Haifeng Wang

Institution: East China University of Science and Technology

Language: English

Topic: Ammonia Synthesis and Nitrogen Reduction

Subfield: Catalysis

Field: Chemical Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,500

Funders: Science and Technology Commission of Shanghai Municipality, National Key Research and Development Program of China, Fundamental Research Funds for the Central Universities