Ascorbic acid-assisted hydrothermal route to create mesopores in polymeric carbon nitride for increased photocatalytic hydrogen generation

The facile synthesis of mesoporous polymeric carbon nitride (PCN) can enlarge the surface area and provide mass transport channels, which thus potentially boosts its photocatalytic H-2 generation. However, the formation of mesopores in PCN are mainly relying on the hard and soft templates with tedious operations, and it remains a grand challenge in preparing mesoporous PCN without the assistance of templates. Herein we report on an ascorbic acid-assisted hydrothermal route to effectively create the mesoporous in bulk PCN. The mesopores thus formed a typical IV isotherm with an H-3 hysteresis loop, and have a pore size distribution of similar to 3.8 nm. Moreover, the crystallinity of mesoporous PCN was improved with ascorbic acid-assisted hydrothermal treatment. Meanwhile, ascorbic acid can be converted to carbon materials under hydrothermal conditions. As a result, an increased photocatalytic H-2 generation was realized under visible light exposure. The highest H-2 generation rate is up to 26.8 mmol h(-1) for Pt/CN-A10%, near 10 times higher than that of Pt/ PCN (2.7 mmol h(-1)). This work highlights the effectiveness of organic acid-assisted hydro thermal treatment for synthesizing mesoporous PCN for increased photocatalytic performance. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.