Piezoelectric activation of dual lattice-oxygen mechanism through OH− Grotthuss transport in water electrolysis

The realization of multi-energy water oxidation systems is impeded by the challenge of integrating multiple energy inputs. Here, we overcome this limitation via ultrasonic pre-treatment of the electrolyte, which triggers a mechano-electrochemical coupling effect through piezoelectric polarization. This process promotes a Grotthuss-type OH− state that weakens O-H bonds and increases the interfacial OH− concentration, thereby influencing the electrochemical reconstruction of Ni(OH)2 to NiOOH and modifying water electrolysis pathways. These changes enhance Ni-O covalency and synergistically activate two low-energy water oxidation pathways on NiOOH involving lattice oxygen: one couples lattice oxygen with adsorbed oxygen, while the other facilitates direct lattice oxygen-oxygen coupling. Both routes bypass the high-energy *OOH intermediate typical of the conventional adsorbate evolution mechanism (*OH → *O → *OOH → O2), with the latter also avoiding *O adsorption entirely. Notably, just one minute of ultrasonic stimulation reduces the overpotential by 222 mV at 100 mA cm-2. This pulsed-energy strategy thus offers an efficient and scalable approach to realizing multi-energy-enhanced water splitting. The challenge of integrating multiple energy inputs impedes multi-energy water oxidation. Here, the authors report a pulsed-energy strategy using ultrasonic pretreatment for transient electrolyte polarization, promoting the Grotthuss-type OH− transport and activating dual low-energy lattice oxygen pathways.