The development of stable and highly efficien multifunctional electrocatalysts for the hydrogen evolution reaction （HER）,oxygen reduction reaction （ORR） and oxygen evolution reaction （OER） are essential for the efficient conversion and storage of renewable energy.The significant advantages of single-atom catalysts,such as strong metal slab interactions,unsaturated coordination and efficient atomic utilization,have opened new avenues for designing multifunctional catalysts.Herein,based on density functional theory,a single atom doped PdPX system was designed as a multifunctional electrocatalyst,which demonstrated the synergistic effect between defects and transition metal atoms and led to enhanced catalytic performance.The results showed that PdPS/PdPSe with P/X vacancy,PdPTe with P/Pd vacancy and Co/Rh/Ir@PdPX exhibited promising HER activity.Co@PdPS（Se）,with an overpotential of 0.56（0.44） V,was predicted to be a promising OER catalyst.Moreover,Rh（Ir）@PdPS（Se）catalysts exhibited efficient catalytic properties for ORR Besides,Co@PdPS（Se）,Rh（Ir）@PdPSV（S）,Co@PdP-SeV（Se）and Ir@PdPSV（S）-1 exihibited multifunctional catalytic performance with moderate overpotential.Next,the origin of catalytic activity was revealed by using the crystal orbital Hamilton populations theory.For a strong adsorption system,proper filling of the anti-bonding state can increase the energy of the system,weaken the adsorption strength,and facilitate the desorption of intermediates Conversely,augmenting bonding states can enhance its adsorption capacity.These findings provide theoretica guidance for the design and fabrication of novel multifunctional electrocatalysts in terms of filling of bondingstate.
