A compact photoreactor for automated H2 photoproduction: Revisiting the (Pd, Pt, Au)/TiO2 (P25) Schottky junctions

The configuration and geometry of chemical reactors underpins the accuracy of performance evaluation for photocatalytic materials and, accordingly, the development and validation of thermodynamic and kinetic model reactions. The lack of accurate photonic, mass, and heat transport profiles for photochemical reactors hinder standardization, scale-up, and ultimately comparison between different experiments. This work proposes two contributions at the interface between engineering of chemical process and materials science: (A) an automated compact stainless-steel photoreactor with 40 cm3 and 65 cm2 of volume and area, respectively, for hydrogen photoproduction as a model reaction and (B) the synthesis, characterization, and performance of TiO2 Schottky junctions, using Pd, Pt, or Au nanoparticles (ca. 0.5, 1, 2 wt% loadings each) to validate the operation of the reactor. A photonic profile methodology is implemented to the studied reactor to obtain the local light absorption profile, opening up for evaluation of the local quantum yield calculation for the selected materials. A combi-nation of transmission electron microscopy, (X-ray/ultraviolet) photoelectron/electron, energy loss/infrared spectroscopies, X-ray scattering, inductively coupled plasma atomic emission spectroscopy, and ultra-violet-visible spectrophotometry is employed to determine the distinctive surface and bulk properties to build structure-function correlations. The (Pd, Pt, Au)/TiO2 Schottky junction exhibits H2 production rates slightly higher than previous studies, with quantum yields almost 2-fold higher than reported values. These results, demonstrate that the proposed novel geometry of the photoreactor improves the photonic, heat, and mass profiles. An in-depth analysis of the Au plasmon was investigated coupling electron energy loss spectroscopy, UV-vis, and transmission electron microscope, resulting in insightful information about the Au NP mode at the TiO2 interface.

Automated summary

The configuration and geometry of chemical reactors significantly impact performance evaluation and the development of thermodynamic and kinetic model reactions for photocatalytic materials. Lack of accurate transport profiles for mass, heat, and photons in photochemical reactors hinders comparison between experiments and standardization. This study proposes a compact stainless-steel photoreactor for hydrogen photoproduction and uses TiO2 Schottky junctions with Pd, Pt, or Au nanoparticles to validate the reactor's operation. Results show improved profiles and increased quantum yields compared to previous studies.