Eliminating Trap‐States and Functionalizing Vacancies in 2D Semiconductors by Electrochemistry

Abstract

One major challenge that limits the applications of 2D semiconductors is the detrimental electronic trap states caused by vacancies. Here using grand‐canonical density functional theory calculations, a novel approach is demonstrated that uses aqueous electrochemistry to eliminate the trap states of the vacancies in 2D transition metal dichalcogenides while leaving the perfect part of the material intact. The success of this electrochemical approach is based on the selectivity control by the electrode potential and the isovalence between oxygen and chalcogen. Motivated by these results, electrochemical conditions are further identified to functionalize the vacancies by incorporating various single metal atoms, which can bring in magnetism, tune carrier concentration/polarity, and/or activate single‐atom catalysis, enabling a wide range of potential applications. These approaches may be generalized to other 2D materials. The results open up a new avenue for improving the properties and extending the applications of 2D materials.

Operando formation of highly efficient electrocatalysts induced by heteroatom leaching

“…As shown in Supplementary Fig. 31 55 – 57 , the obtained leaching Pourbaix diagram reveals that the F- and N-dopants leach at either too high or too low potential ranges while a relatively stable potential interval exists in the middle range of the voltage, which is in good agreement with the experimental outcomes (Fig. 4 ).…”

Atomistic Understanding of Two-dimensional Electrocatalysts from First Principles

“…The essence of the CHEM is that the free energy of solvated ion, which is difficult to directly calculate from first-principles, can be deduced from the equilibrium reaction where the energies of other species can be more easily calculated or have been experimentally measured. This idea is not limited to a proton but can be extended to other ions . For example, the free energy of 1 M Fe 2+ in aqueous solution can be obtained through the reaction at equilibrium: where the subscript “s” denotes the solid state.…”

“…This idea is not limited to a proton but can be extended to other ions. 14 For example, the free energy of 1 M Fe 2+ in aqueous solution can be obtained through the reaction at equilibrium: where the subscript "s" denotes the solid state. Therefore:…”

Fabrication of Mn/P co-doped hollow tubular carbon nitride by a one-step hydrothermal–calcination method for the photocatalytic degradation of organic pollutants

“…Therefore, according to the formula E CB = E fb − 0.2 V (ref. 65) and the potential conversion formula E (NHE) = E (Ag/AgCl) + 0.197 V, 66 the E CB values of CN, Mn–CN, PCN, and 3Mn–PCN are −0.743, −0.863, −0.913, and −1.343 V (V vs. NHE), respectively. On the basis of the formula E VB = E CB + E g , 67 the valence band potential ( E VB ) of CN, Mn–CN, PCN, and 3Mn–PCN are 1.847, 1.697, 1717, and 1.107 V (V vs. NHE), respectively.…”