Regulating Pt-covalent triazine framework Schottky junctions by using tailor-made nitrogen sites towards efficient photocatalysis

Abstract

Covalent triazine frameworks (CTFs) with designable nitrogen-rich structures, which can form Schottky junctions with Pt nanoparticles, have been extensively studied in photocatalysis. However, tuning the interaction inside the Schottky junction to inhibit charge recombination and promote charge migration for better photocatalytic performance in CTFs is rarely explored. Herein, we report a new strategy to regulate the Schottky junction structures between CTFs and Pt nanoparticles by using tailor-made modulating nitrogen sites in Pt@CTFs. We found that the isolated singular pyridine sites are good for the photocatalytic hydrogen production performance, while the neighboring bipyridine sites are detrimental to the photocatalytic performance. We further explored the influence of the number and position of pyridine N units on the band structures of the CTFs and found that the CTF (CTF-Py-1) with isolated single pyridine sites can form more effective Schottky junctions with Pt nanoparticles, comprising the smallest Schottky barrier to facilitate the electrons transport inside the junction. Consequently, Pt@CTF-Py-1 gives the best photocatalytic performance among the series with a hydrogen production rate of 14 960 μmol h⁻¹ g⁻¹, which is about ten times higher than that of Pt@CTF-BPy. This study provides a new insight for designing Schottky junction photocatalysts by modulating nitrogen-containing organic units.