Modulation of the Chemical Microenvironment at the Hematite-Based Photoanode Interface with a Covalent Triazine Framework for Efficient Photoelectrochemical Water Oxidation

Transferring charge between the hematite photoanode and cocatalyst interface for efficient photoelectrochemical water oxidation is a big obstacle. However, the chemical microenvironment at the interface plays an important role in this field. Here, we used a covalent triazine framework (CTF-BTh) containing a bithiophene moiety to modulate the microenvironment at the interface between Gd-doped hematite and the cobalt silicate cocatalyst. Detailed studies show that Gd doping increases the donor density and reduces the charge transfer resistance. Furthermore, the coordination bonds (N-Co and S-Co) provide pathways for charge flow and also enhance the average oxidation state of Co. The conjugated system of the CTF-BTh is also easy for electron delocalization. These modifications effectively passivate the surface state and synergistically suppress the electron-hole recombination. This work provides a universal strategy for improving the interfacial microenvironment to achieve efficient water oxidation.

Automated summary

The chemical microenvironment at the interface plays a crucial role in efficient photoelectrochemical water oxidation. In this study, a covalent triazine framework was used to modulate the interface microenvironment between Gd-doped hematite and the cobalt silicate cocatalyst. Gd doping increased the donor density and reduced charge transfer resistance, while coordination bonds provided pathways for charge flow and enhanced the average oxidation state of Co. The conjugated system of the framework allowed for easy electron delocalization. These modifications effectively passivated the surface state and suppressed electron-hole recombination.