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 → O 2 ), 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.