Boosting charge-transfer in tuned Au nanoparticles on defect-rich TiO2 nanosheets for enhancing nitrogen electroreduction to ammonia production

Peng Yang; Heng Guo; Haoran Wu; Fengying Zhang; Jiaxin Liu; Mengyue Li; Yuantao Yang; Yuehan Cao; Guidong Yang; Ying Zhou

doi:10.1016/j.jcis.2023.01.002

Boosting charge-transfer in tuned Au nanoparticles on defect-rich TiO₂ nanosheets for enhancing nitrogen electroreduction to ammonia production

J Colloid Interface Sci. 2023 Apr 15:636:184-193. doi: 10.1016/j.jcis.2023.01.002. Epub 2023 Jan 5.

Authors

Peng Yang¹, Heng Guo², Haoran Wu¹, Fengying Zhang³, Jiaxin Liu¹, Mengyue Li¹, Yuantao Yang¹, Yuehan Cao¹, Guidong Yang⁴, Ying Zhou⁵

Affiliations

¹ School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China.
² State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China; School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China. Electronic address: heng.guo@swpu.edu.cn.
³ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China; School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China.
⁴ XJTU-Oxford International Joint Research Laboratory of Catalysis, School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an 7010049, China.
⁵ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China; School of New Energy and Materials, Southwest Petroleum University, Chengdu 610500, China; Tianfu Yongxing Laboratory, Chengdu 611130, China. Electronic address: yzhou@swpu.edu.cn.

PMID: 36634390
DOI: 10.1016/j.jcis.2023.01.002

Abstract

The electrocatalytic nitrogen reduction reaction (eNRR) to ammonia (NH₃) has been recognized as an effective, carbon-neutral, and great-potential strategy for ammonia production. However, the conversion efficiency and selectivity of eNRR still face significant challenges due to the slow transfer kinetics and lack of effective N₂ adsorption and activation sites in this process. Herein, we designed and fabricated defect-rich TiO₂ nanosheets furnished with oxygen vacancies (OVs) and Au nanoparticles (Au/TiO_2-x) as the electrocatalyst for efficient N₂-fixing. The experimental results demonstrate that OVs act as active sites, which enable efficient chemisorption and activation of N₂ molecules. The Au nanoparticles loaded on the OVs-rich TiO₂ nanosheets not only accelerate charge transfer but also change the local electronic structure, thus enhancing N₂ adsorption and activation. In this work, the optimal Au/TiO_2-x electrocatalyst displays a considerable NH₃ yield activity of 12.5 μg h^-1 mg_cat.^-1 and a faradaic efficiency (FE) of 10.2 % at -0.40 V vs reversible hydrogen electrode (RHE). More importantly, the Au/TiO_2-x exhibits a stable N₂-fixing activity in cycling and it persists even after 80 h of consecutive electrolysis. Density functional theory (DFT) calculations reveal that the OVs serve as the active sites in TiO₂, while Au nanoparticles are crucial for improving N₂ chemisorption and lowering the reaction energy barrier by facilitating the charge transfer for eNRR with a distal hydrogenation pathway. This research offers a rational catalytic site design for modulating charge transfer of active sites on metal-supported defective catalysts to boost N₂ electroreduction to NH₃.

Keywords: Ammonia; Au; Electrochemical N(2) reduction; Oxygen vacancy; TiO(2).