Immobilisation of graphitic carbon nitride onto aluminium-based microfluidic reactors for artificial photosynthesis: Comparative analysis of deposition techniques and photocatalytic performance

This research investigates the immobilisation of graphitic carbon nitride (g-C₃N₄) onto aluminium-based microfluidic reactors (MFRs) for application in artificial photosynthesis. The study focuses on developing efficient, stable, and scalable methods to anchor g-C₃N₄ onto microreactor surfaces to enhance photocatalytic performance and long-term operational stability. Three distinct immobilisation techniques have been employed: chemical vapour deposition (CVD), anodisation combined with the sol–gel technique, and physical vapour deposition (PVD). Each method offers different degrees of coating adhesion, uniformity, and porosity, thereby influencing the photocatalytic efficiency of the reactor system.

Comprehensive characterisation of the immobilised catalyst layers has been conducted using Brunauer–Emmett–Teller (BET) surface area analysis, atomic force microscopy (AFM), and scanning electron microscopy (SEM). These techniques provided detailed insights into surface area, morphology, porosity, and nanoscale roughness. The topographical data obtained from AFM have been reconstructed into three-dimensional geometries using finite element method (FEM) software to enable a realistic simulation of fluid flow and light-matter interactions within the microchannels.

A coupled multi-physics model incorporating reaction kinetics, optical absorption, and laminar flow dynamics was developed to simulate artificial photosynthesis under various operational conditions. This model has been experimentally validated for each coating type, establishing a strong correlation between simulation and experimental outcomes.

Comparative analysis of reaction rates, catalyst layer roughness, coating thickness, and catalyst leaching behaviour has been performed to determine the most effective immobilisation approach. The findings provide a fundamental understanding of how immobilisation technique influences catalytic performance and stability, offering valuable guidelines for designing efficient MFR-based systems for solar-to-chemical energy conversion and sustainable artificial photosynthesis applications.