Enhanced Hydrogen Evolution Reaction Performances of Ultrathin CuBi₂O₄Nanoflakes

Semiconductor catalysts play a potential role for efficient electrocatalytic hydrogen production. In this work, copper bismuth oxide (CuBi2O4) nanostructures were synthesized via the coprecipitation method using two different Cu precursors: one is Cu(NO3)3·9H2O and the other is CuCl2. When using Cu(NO3)3·9H2O, the sample showed an interconnected and aggregated irregular spherical CuBi2O4 nanoparticle structure. On the other hand, the CuCl2-derived CuBi2O4 sample exhibited an interconnected ultrathin nanoflake structure. The CuBi2O4 nanoflakes displayed a higher electrochemically active surface area (160 cm2) than the CuBi2O4 nanoparticle (116 cm2). Accordingly, the CuBi2O4 nanoflakes revealed an excellent hydrogen evolution reaction performance with a low Tafel slope (117 mV/dec) and a small overpotential (384 mV at 10 mA/cm2 in 1 M KOH). These results specify that the CuBi2O4 nanoflakes are a suitable electrocatalyst material for high-performance water splitting.