Electrochemical evolution of size-controlled Pd nanocubes during long-term electrocatalytic hydrodechlorination reaction

Electrocatalytic hydrodechlorination (EHDC) emerges as a promising technology for remediating chlorinated organic pollutants, garnering considerable attention. However, the long-term performance evolution of EHDC, specifically its size-dependent aspect, remains relatively unexplored. This work aims to address this gap by examining Pd nanocubes with controlled sizes of 7.2 nm for Pd Cube-S, 10.6 nm for Pd Cube-M, and 14.7 nm for Pd Cube-L. The specific activity and electrochemical turnover frequency (TOF) of these Pd cubes increased with particle size, a pattern that is inverse to the trend of mass activity. Although Pd Cube-S initially demonstrated heightened EHDC efficiency, a long-term examination over multiple EHDC cycles revealed that Pd Cube-L exhibited escalating mass activity (from 2.10 to 3.11 min−1 g−1 after 5 cycles) and maintained stability over 180 h of continuous electrolysis. This phenomenon arose from structural reorganization of Pd cubes occurring during the EHDC cycles, leading to an expansion of the electrochemically specific surface area. Such structural reorganization brought about more enhancements in large-sized Pd cubes, whereas Pd Cube-S suffered more from particle agglomeration. Consequently, by fine-tuning the particle size, this work provided valuable insights into the long-term EHDC process, offering practical implications for enhancing the durability of Pd nanocatalysts.