Elevating Nitrate Reduction through the Mastery of Hierarchical Hydrogen-Bond Networks

To effectively resolve environmental and industrial dilemmas, electrochemical reduction of nitrate (NO3-) to ammonia (NH3) offers a brilliant strategy for tackling pollution and creating economic value, but the scarcity and reduced reactivity of available interfacial water and reactive adsorbates represent ongoing obstacles. Here, we reform the water-ion networks via electrolyte concentration manipulation and electrode construction on atomically flat Au single-crystal surfaces. With the combination of in situ Raman spectroscopy and multifidelity theoretical simulations, we pinpoint H2O with dual hydrogen-bond donors as an observable indicator for nitrate electroreduction (NO3RR). A hierarchical configuration characterized by structured Li+·NO3- planes coupled with enriched hydrogen-bond networks is verified to streamline the reactive intermediates activation and proton transport, thus synergistically boosting NO3RR. We highlight the cooperative modulation of the interfacial water-ion interactions and the hydrogen-bond networks in optimizing NO3RR. Our findings unveil microscale viewpoint of synergy between the local ion-water interactions and connectivity of the hydrogen-bonding network.