In Situ Electrochemical Fabrication of Ultrasmall Ru-Based Nanoparticles for Robust N2H4 Oxidation

Ultrasmall Ru nanoparticles is expected as a potential alternative to Pt for efficient hydrazine oxidation (HzOR). However, preparation of ultrasmall and well-distributed Ru nanoparticles usually suffered from the steps of modification of supports, coordination, reduction with strong reducing reagents (e.g., NaBH4) or pyrolysis, imposing the complexity. Based on the self-reducibility of C-OH group and physical adsorption ability of commercial Ketjen black (KB), we developed an efficient, stable and robust Ru-based electrocatalyst (A-Ru-KB) by coupling impregnation of KB in RuCl3 solution and simple in situ electrochemical activation strategy, which endowed the formation of ultrasmall and well-distributed Ru nanoparticles. Benefiting from an enhanced exposure of Ru sites and the faster mass transport, A-Ru-KB achieved 63.4 and 3.9-fold enhancements of mass activity compared with Pt/C and Ru/C, respectively, accompanied by a similar to 144 mV lower onset potential and faster catalytic kinetics than Pt/C. In the hydrazine fuel cell, the open-circuit voltage and maximal mass power density of A-Ru-KB was 130 mV and similar to 3.8-fold higher than those of Pt/C, respectively, together with the long-term stability. This work would provide a facile and sustainable approach for large-scale production of other robust metal (electro)catalysts with ultrasmall nanosize for various energy conversion and electrochemical organic synthesis.

Automated summary

By coupling impregnation and electrochemical activation, an efficient, stable, and robust Ru-based electrocatalyst with ultrasmall and well-distributed Ru nanoparticles was developed, showing superior performance compared to Pt-based and Ru-based catalysts.