Self‐Optimized Acidic Ceramic TiB 2 Electrocatalyst: In Situ Electrochemical Exfoliation for Enhanced Hydrogen Evolution

ABSTRACT TiB 2 , a layered transition metal diboride with exceptional electronic conductivity and acid‐resistant stability, has emerged as a promising electrocatalyst for acidic hydrogen evolution reactions (HER). However, its stacked crystalline architecture inherently limits active site availability and mass transport efficiency, necessitating high operating overpotentials. We report a spontaneously optimizing TiB 2 electrocatalyst through in situ electrochemical exfoliation during sustained HER operation in acidic media. Continuous potential‐driven ion intercalation triggers structural exfoliation of bulk TiB 2 into lamellar nanosheets, simultaneously achieving—59% overpotential reduction (from 924 to 451 mV @10 mA cm −2 ) and a 10 3 ‐fold active site density increase. This self‐optimization mechanism, revealed through characterization, originates from ion‐induced interlayer electrostatic weakening and concomitant electronic structure modulation. Our findings establish an electrochemical activation strategy for layered borides, transitioning them from static precatalysts to dynamic active‐phase systems.