Potential reversible reactions over PdNix alloy catalysts: Hydrogen evolution from formic acid and formic acid formation by CO2 reduction reaction

A novel approach is required to achieve effective CO2 utilization. This study demonstrates a new approach for the reversible reaction in the CO2-HCOOH cycle, that is, FA decomposition and CO2 reduction, under ambient pressure using Pd-based alloy catalysts. First, Pd-based alloys (Pd-M; M = Co, Ni, and Zn) were screened for FA decomposition; the PdNi alloy showed superior catalytic activity compared to Pd and the other alloys. Second, Pd3Ni, PdNi, and PdNi3 were prepared to understand the composition-dependent activity of the PdNix series. DFT calculations provided insight into why the PdNix alloys show higher catalytic activities for FA decomposition than Pd. Finally, the electrochemical CO2 reduction reaction was investigated, and the PdNix alloy catalysts showed superior selectivity for FA formation compared to Pd catalysts. Thus, this study provides a novel strategy for CO2 utilization using bimetallic Pd-Ni heterogeneous catalysts.