Thermal responsive Rh1-Pd single-atom catalyst for controlling activity in direct formic acid fuel cells.

Single-atom catalysts are highly active for specific reactions; however, their sinter-resistance and clean surfaces make it difficult to impart them with a "smart" property. Herein we design a thermosensitive single-atom Rh1-Pd nanosheets (NSs) by employing amino functionalized poly(N-isopropylacrylamide) as thermal responsive gate for the "open"/"closed" control of electro-catalytic activity. Using formic acid electro-oxidation as model reaction, the thermosensitive Rh1-Pd NSs exhibit high mass activity (2.29 A mgPGM-1), strong poisoning resistance, and reversible thermo-responsibility at a lower critical solution temperature (LCST) of 35 oC. In-situ spectroscopy and theoretical investigations reveal that the d-electron deficient Rh1-Pd NSs favor the direct formate pathway and weaken the binding of self-poisonous species, contributing to the high activity and anti-self-poisoning talent. Most importantly, for the direct formic acid fuel cells (DFAFCs), the thermosensitive Rh1-Pd NSs exhibit a high power density operated below the LCST, while the power drops sharply once above the LCST, realizing the intelligent battery thermal protection for DFAFCs.