Stabilization of Pt Single Atoms on Ni(OH)₂/C with Abundant Ni Vacancies for Clean Energy and Valuable Chemicals in Direct Methanol Fuel Cells

The challenges in direct methanol fuel cells (DMFCs) arise from using traditional noble metal anode catalysts, which result in unwanted CO2 emissions. Developing single-atom catalysts (SACs) with high metal loading is crucial for partial methanol oxidation to formate while reducing CO2 emissions. However, this faces difficulties like sintering and CO poisoning of single atoms (SAs) during methanol oxidation reaction (MOR). Though using support vacancies to stabilize metal atoms shows promise for SAC synthesis, cation vacancy defects, especially for methanol oxidation, have received little attention. Here, we have prepared PtSA on a Ni(OH)2/C support with abundant Ni vacancies (PtSA–Ni(OH)2/C–VNi) as an anode catalyst. The DMFC with this catalyst provides outstanding results of 613.83 mA cm–2 current and 79.5 mW cm–2 power densities at the potential of 0.63 V with 99.63% Faraday efficiency for formate production at 70 °C, with a minimum amount of CO2 emissions. Pt atoms on VNi drive methanol adsorption and CO detoxification, enhancing partial methanol oxidation to formate. DFT further confirmed that methanol favorably forms formate instead of CO2 in PtSA–Ni(OH)2/C–VNi due to a lower energy barrier (1.08 eV) for OCH conversion to HCOOH. This study provides a way for developing high-performance, CO2-free SA-based anode catalysts for DMFCs.