Interfacial Nanobubbles’ Growth at the Initial Stage of Electrocatalytic Hydrogen Evolution

Bubble evolution in electrolysis commonly initiates from nanobubbles (NBs), and their ultrasmall size induces unique high internal pressure and consequently high anti-potential, namely, the extra overpotential, which is of great significance but still remains rather vague. Herein, we employ the in situ electrochemical surface plasmon resonance imaging method as combined with atomic force microscopy measurement to track the formation and growth of interfacial NBs during initiative hydrogen evolution reaction. We find that NBs’ growth initiate from pancake shaped ones with increasing coverage and roughly pinned three-phase boundaries and increasing contact angle and height, but the coverage remains almost unchanged after reaching equilibrium state; Further increasing overpotential leads to the rise of NBs’ curvature (anti-potential), as well as higher gas outflux rate, namely, higher background current. As confirmed by molecular dynamics simulation, the “pin-rise” growth mode and the quantitative influence of NBs on the electrochemical performance has been revealed.