• • Grain boundary engineering in HENCs enhances catalytic activity by providing abundant active sites; e.g., Pt-based nanocrystals with controlled grain boundaries exhibit up to 10-fold increase in mass activity for ORR compared to commercial Pt/C.
• • Single-atom alloys (SAAs) maximize noble metal utilization; Pt single atoms on Cu supports achieve 100% CO selectivity in CO2RR at -0.5 V vs. RHE, with turnover frequency (TOF) of 0.8 s^-1.
• • Intermetallic compounds with ordered structures improve stability; PtCo intermetallic nanoparticles retain 92% of initial activity after 30,000 potential cycles in acidic media, outperforming disordered alloys.
• • Amorphous HENCs exhibit superior corrosion resistance; amorphous Pd-based catalysts maintain 95% H2O2 selectivity over 10 h operation, demonstrating potential for industrial electrosynthesis.