Laser Photochemistry Laboratory

192. Manifolding surface sites of compositional CoPd alloys via pulsed laser for hydrazine oxidation-assisted energy-saving electrolyzer: Activity origin and mechanism discovery
Yujeong Jeong†, Shreyanka Shankar Naik†, Jayaraman Theerthagiri†, Cheol Joo Moon†, Ahreum Min, M. L. Aruna Kumari, Myong Yong Choi*

Chemical Engineering Journal
Vol, Part
Page Number
144034 (2023)
Publication Year

15 August 2023
IF(2022): 15.1
JCR: 96.8%
2019R1A6C1010042, 2021R1A6C103A427, 2022R1A2C2010686, 2022R1A4A3033528, 2021R1I1A1A01060380, 2019H1D3A1A01071209

Energy-driven overall water splitting (OWS) for renewable hydrogen generation is 

critical for carbon neutrality. However, the OWS electrolyzer efficiency is significantly 

affected by the kinetically sluggish anodic oxygen evolution reaction (OER). An efficient 

approach is proposed to promote energy-saving hydrogen production by using a 

composition-dependent multifunctional CoPd alloy via pulsed laser ablation in liquids, 

where the OER is replaced with the hydrazine oxidation reaction (HzOR). The CoPd 

alloy improves N2H4 chemisorption onto the surface via dative bonding between the 

lone pair electrons of N and the empty 5s orbital of Pd and 3d of low spin Co. The 

optimal Co1Pd9 alloy sample demonstrates excellent hydrogen evolution reaction and 

HzOR with the lowest overpotentials of 0.224 and 0.329 V at 10 mA/cm2 in 1.0-M KOH 

and 1.0-M KOH/0.5-M N2H4, correspondingly. An in situ/operando Raman study 

reveals that metal active site and structural transformation occurred during the 

oxidation (M*-O) and reduction (M*-H) reactions under an alkaline medium. Besides, 

the overall hydrazine splitting performed using the Co1Pd9 ‖ Co1Pd9 electrolyzer 

requires a cell voltage of ~0.228 V only at 10 mA/cm2 with remarkable electrochemical 

and structural stability over 10 h, which is significantly lower than that of the traditional 

OWS electrolyzer (~1.837 V). This study demonstrates the practical use of CoPd alloys 

in direct N2H4 fuel cells to produce both H2 fuel and electrical energy.