Insight Into the Porphyrin‐Modulated Interfacial Charge Transfer Kinetics Behavior of Molybdenum Disulfide Nanostructures by Scanning Photoelectrochemical Microscopy

Hydrogen generation through electrocatalytic water decomposition using semiconductor electrocatalysts is considered a promising approach, which is expected to replace fossil fuel. Transition metal dichalcogenides, especially MoS 2 ‐based catalysts, have been considered as the state‐of‐the‐art hydrogen evolution reaction electrocatalysts due to favorable catalytic activity. However, obtaining metastable phase MoS 2 nanomaterials with high purity remains a great challenge. Additionally, since most of the generally prepared MoS 2 is a mixed phase, it often fails to exhibit any type of superior catalytic performance. Herein, 5, 10, 15, 20‐Tetrakis (4‐hydroxyphenyl) porphyrin (THPP) was used as an electron donor to modify semiconducting phase 2H–MoS 2 . After the modification, the catalytic properties of 2H–MoS 2 are shifted toward those of metallic phase 1T–MoS 2 . We investigated charge transfer kinetic behavior from a microscopic point of view with the help of in situ scanning photoelectrochemical microscopy (SPECM). It is found that 2H–MoS 2 /NiS 2 /THPP exhibits significantly higher charge transfer rate constant of 0.35 × 10 −2 cm s −1 , which is more than three times that of 2H–MoS 2 /NiS 2 . The enhanced charge transfer kinetics is attributed to the introduction of the porphyrin acting as a charge transporting mediator, which accelerates rapid charge transfer, thereby inhibiting charge carrier recombination and enhancing charge separation.