Determination of optimum Pd:Ni ratio for Pd x Ni 100‐ x / CNT s formic acid electrooxidation catalysts synthesized via sodium borohydride reduction method

Summary The main purpose of this study is to investigate the optimum Pd:Ni molar ratio for carbon nanotube–supported PdNi (Pd x Ni 100‐ x /CNT) alloy catalysts toward formic acid electrooxidation (FAE). NaBH 4 reduction method was employed for the synthesis of Pd 90 Ni 10 /CNT, Pd 70 Ni 30 /CNT, Pd 50 Ni 50 /CNT, and Pd 40 Ni 60 /CNT. Synthesized catalysts were characterized by employing advanced surface analytical techniques, namely, X‐ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption‐desorption, and inductively coupled plasma–mass spectrometry (ICP‐MS). The characterization results showed that all catalysts were successfully synthesized at desired molar composition. Pd 90 Ni 10 /CNT displayed the highest specific and mass activities with 2.32 mA/cm 2 and 613.9 mA/mg Pd, respectively. Specific activity of the Pd 90 Ni 10 /CNT was found approximately 3.6, 2.3, 11.1, and 3.4 times higher than those of Pd 70 Ni 30 /CNT, Pd 50 Ni 50 /CNT, Pd 40 Ni 60 /CNT, and Pd/CNT, respectively. The synergistic effect between Pd and Ni at optimized metal ratio was utilized to obtain an improvement in specific activity. Furthermore, Pd 90 Ni 10 /CNT showed the lowest charge transfer resistance ( R ct ) and a long‐term stability. To our knowledge, this is the first study reporting the optimization of atomic molar composition for Pd x Ni 100‐ x /CNT catalysts toward FAE.