Interface-Dependent Nitrite-to-Ammonia Reduction in a Cu/Pd Palladium Membrane Reactor

Authors

• Bingxin Guo, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China.
• Yaxin Shi, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China.
• Shihe Lin, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China.
• Zhiqin Liang, School of Physical Science and Engineering, Beijing Jiaotong University, Beijing 100044, P. R. China; Tangshan Research Institute of Beijing Jiaotong University, Tangshan, Hebei 063000, P. R. China.Follow

Document Type

Article

Corresponding Author(s)

Zhiqin Liang([email protected])

Abstract

Nitrite-to-ammonia conversion is a multistep reduction that requires hydrogen delivery together with a suitable interfacial electrochemical environment. Palladium membrane reactors (PMRs) spatially separate hydrogen supply from the substrate, but whether a hydrogen-rich membrane interface alone can sustain this deep reduction remains unclear. Here, we systematically compared the hydrogenation and electrolysis sides of a Cu/Pd PMR. On the hydrogenation side, NH₃ was barely formed; representative Cu/Pd samples gave only 1.90-2.16 μg h^-1 cm^-2 after 9 h, with apparent Faradaic efficiencies below 2%. The weak response persisted under sustained electrochemical hydrogen charging and in direct-H₂ open-circuit controls, although differences in interfacial hydrogen availability may still contribute. On the electrolysis side, Cu modification gave markedly higher activity with clear dependences on potential, Cu loading, and pH. Under optimized electrolysis-side conditions, 0.5 mg cm^-2 Cu in alkaline electrolyte at -1.2 V vs. RHE gave an NH₃ yield rate of 1140.38 μg h^-1 cm^-2. In the three-compartment PMR open-circuit controls, the NH₃ yield rate was only 0.24-1.61 μg h^-1 cm^-2, more than two orders of magnitude lower. We therefore propose a “spatial-mechanistic compatibility” model: the reaction site in a PMR is not governed solely by hydrogen flux, but by how well the interfacial functionality matches the mechanistic demands of the target reaction.

Graphical Abstract

Keywords

Cu/Pd interface, Nitrite reduction, Palladium membrane reactor, Proton-coupled electron transfer, Reaction-site selection

DOI

10.61558/2993-074X.3630

Online Date

9-15-2026

Recommended Citation

Bingxin Guo, Yaxin Shi, Shihe Lin, Zhiqin Liang. Interface-Dependent Nitrite-to-Ammonia Reduction in a Cu/Pd Palladium Membrane Reactor[J]. Journal of Electrochemistry, doi: 10.61558/2993-074X.3630.