Hydrogenated TiO₂ Nanoparticles Loaded with Au Nanoclusters Demonstrating Largely Enhanced Performance for Electrochemical Reduction of Nitrogen to Ammonia

Abstract

Pristine TiO2/Au (P‐TiO2/Au) is modified by hydrogen plasma (H‐TiO2/Au) or hydrogen and oxygen plasma (H‐O‐TiO2/Au) treatment, and then used as electrochemical catalysts for nitrogen reduction reaction (NRR). H‐TiO2/Au shows enhanced performance for the NRR process compared with both P‐TiO2/Au and H‐O‐TiO2/Au. After hydrogenation treatment, some disordered regions on the surface of TiO2 nanoparticles are formed, and a large number of oxygen vacancies are incorporated into the TiO2 crystalline structures. When the samples are used as catalysts for electrochemical NRR, the yield of NH3 of H‐TiO2/Au is about ten times compared to that of P‐TiO2/Au and about three times that of H‐O‐TiO2/Au, while the highest Faradaic efficiency of 2.7% is also obtained at the potential of −0.1 V for the H‐TiO2/Au catalyst. The density functional theory (DFT) calculation results confirm that H‐TiO2/Au with oxygen vacancies and the disordered surface layer is much preferred energetically for the NRR process. It proves that enhanced adsorption of N2 molecules on the catalyst and reduced reaction barriers due to the presence of defects play an important role in improving catalysts’ performances. The results show that the plasma hydrogenation technique can be used as an efficient method to modify catalysts for electrochemical NRR processes.

Integration of Multijunction Absorbers and Catalysts for Efficient Solar‐Driven Artificial Leaf Structures: A Physical and Materials Science Perspective

“…As one promising approach, composites consisting of defect-engineered metal oxides (as cocatalysts) decorated with nanocluster catalysts may be considered. [424,425] These hierarchical nanostructures can be fabricated in different ways: 1) preparation of the metal oxide nanostructures on a planar absorber substrate; and 2) conformal coating of the metal oxide thin film on a nanostructured absorber substrate. The structural features and the combination of the composites shall be developed toward improved and efficient HER and OER, respectively.…”

“…As one promising approach, composites consisting of defect‐engineered metal oxides (as cocatalysts) decorated with nanocluster catalysts may be considered. [ 424,425 ]…”

Boosting Electrocatalytic N2 Reduction to NH3 by Enhancing N2 Activation via Interaction between Au Nanoparticles and MIL‐101(Fe) in Neutral Electrolytes

“…[8][9][10] Among the reported Au nanoparticles (Au NPs) catalysts, Au has an unoccupied d-orbital and can accept lone pair electrons from N 2 , which can promote the protonation of reaction intermediates and reduce the reaction energy barrier. [11,12] Meanwhile, the adsorption capacity of Au for H is much weaker than that of Ru, Pd, and Pt, and HER formation tendency is generally low, [13] thus having excellent electrocatalytic activity to promote NRR. [14][15][16] Nevertheless, it is worth noting that Au nanoparticles tend to aggregate, which leads to a decrease in the number of active sites and thus reduces their catalytic activity.…”

“…Metal nanoparticles (NPs) are widely used in electrocatalysis due to their large number of active metal sites [8–10] . Among the reported Au nanoparticles (Au NPs) catalysts, Au has an unoccupied d ‐orbital and can accept lone pair electrons from N 2 , which can promote the protonation of reaction intermediates and reduce the reaction energy barrier [11,12] . Meanwhile, the adsorption capacity of Au for H is much weaker than that of Ru, Pd, and Pt, and HER formation tendency is generally low, [13] thus having excellent electrocatalytic activity to promote NRR [14–16] .…”