Hydrogen-bonded network in interfacial water confer the catalysts with high formic acid decomposition performance

The importance of the dynamic structural evolution of water in the solid–liquid interface cannot be overstated. However, the ubiquitous hydrogen-bonded network is notoriously difficult to probe owing to complex interfacial environment. Formic acid, a fair hydrogen-bond donor and acceptor, is a promising reversible hydrogen storage/release material. Herein, isotope-labeled in-situ mass spectrometry (MS) and operando surface-enhanced Fourier transform infrared measurements (operando FT-IR) reveal the central role of water during formic acid dehydrogenation. The water-promoted restructured HCOONa-Pd@ANI/C catalyst exhibits 100% selectivity, 100% conversion yield with high stability (even after 112 days) under ambient conditions. Coupled to a proton exchange membrane fuel cell, this integrated system reaches a high power density at 29.81 W⋅gPd−1. Our study demonstrates a new pathway involving water, the indispensable proton transfer and exchange through efficiently hydrogen-bonded network in light of operando experimental evidence.