(521ba) High-Resolution Kinetic Analysis of Photocatalytic Water Splitting for Hydrogen Production Using Covalent Organic Framework Catalyst and Ascorbic Acid

Photocatalytic water splitting is a promising sustainable method for hydrogen production, but has been limited by low efficiencies and complex scale-up procedures. The latter is partially attributed to the lack of detailed kinetic data with most studies difficult to be reproduced or validated because of the special experimental configurations and aggregated data presented. Herein, we present a detailed dataset for the photocatalytic water splitting, using an in-house covalent organic framework catalyst and ascorbic acid as the sacrificial agent. The experimental investigation included multiple factors affecting the kinetic characteristics i.e., temperature, photocatalyst loading, sacrificial agent loading, illumination duration and intensity. Moreover, phenomena such as the co-catalyst (Platinum nanoparticles) photodeposition, reactants and products sorption and desorption, and catalyst deactivation were examined in detail. One of the main advantages of the study is the high resolution of temporal hydrogen evolution measurements, employing our lab-scale photoreactor cell coupled with a Residual Gas Analyzer for the collection of mass spectrographs for the evolved gases. In addition, spent photocatalyst was characterized morphologically using high resolution scanning field emission scanning electron microscopy. In parallel, the oxidation kinetics of ascorbic acid were captured with and without the photocatalyst using light spectrometry. The collected data were combined into a three steps apparent kinetic model able to describe the experimental data with an accuracy better than R² 0.75 in most cases. Other literature photochemical kinetic models were tested and fitted on the experimental data in order to assess their applicability in hydrogen production via water splitting.