Ambipolar Enhanced Oxygen Evolution Reaction in Flexible van der Waals LaNiO₃ Membrane

The atomic-level catalysis mechanism of various electrochemical processes can be achieved via the perovskite transition metal oxide (TMO) thin film with accurate stoichiometry and lattice ordering, which boosts the design and engineering of further promising catalysts. In the oxygen evolution reaction (OER), owing to the correlation nature of the TMO, strain can effectively tune the OER performance by modulating the electron occupancy and strengthening the exchange/coupling. However, the surface strain condition declines along with the rapid release of the interfacial lattice mismatch in conventional rigid TMO thin film. This not only restricts obtaining the most prominent strain tunability toward OER but also hinders understanding the fundamental mechanism. Here in this study, we have employed a van der Waals LaNiO₃(LNO) membrane to determine the in situ strain effect on OER performance. We found that the OER activity is dramatically improved with both compressive and tensile strains exhibiting an ambipolar trend. Under only 0.2% compressive and tensile strains, the current densities are, respectively, enhanced ∼121% and ∼92% at 400 mV overpotential, compared with the unstrained LNO scenario. The weakened Ni-O chemisorption and enhanced charge transfer of LNO under varied strain conditions are responsible for this OER enhancement.