Enhanced Electrochemical Oxygen Evolution Reaction Activity on Natural Single-atom Catalyst Transition Metal Phthalocyanine: The Substrate Effect
Oxygen evolution reaction (OER) plays a crucial role in the field of renewable and clean energy such as electric vehicle and fuel cell. The research towards non-noble metals and highly efficient catalysts for OER has garnered wide attention. Here we report a series of macrocyclic transition metals phthalocyanine (TMPc) and transition metal phthalocyanine absorbed oxygen or sulfur atom (TMOPc and TMSPc), natural photocatalytic and electrocatalytic OER single-atom catalysts (SACs). The results demonstrate that they are all semiconductors and extremely stable. Several Pc SACs such as FeOPc and PtPc show excellent high catalytic activity compared with traditional noble metals catalysts and an OER descriptor of Pc SACs is developed to establish the volcano plot. Especially, FeOPc features a low overpotential of only 0.48 V. Moreover, single-walled nanotubes (SWNTs) are employed as the substrate of TMPc to improve the stability of active sites and prevent aggregation. The result indicates that the TMPc single-atom catalysts deposited on SWNT feature more superior OER catalytic performance. Further studies suggest that the enhancement originates from the change of interaction between central TM atom and OER intermediates and the variation of charge transfer caused by SWNT substrates. Our work opens a new avenue of finding OER catalysts with higher activity and lower cost.