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 decompo-sition than Pd. Finally, the electrochemical CO2 reduction reaction was investigated, and the PdNix alloy cat-alysts 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.