Theory-guided assessment of intermittent voltage strategies to enhance electrochemical conversion using 3D microstructured (photo)electrodes

Application of an Intermittent Voltage Perturbation (IVP) offers a promising route to improve the performance of electrochemical systems, yet its impact on microstructured photoelectrodes remains largely unexplored. Here, we investigate IVP on silicon micropillar array photoelectrodes (SiMPs) using a combined theoretical and experimental approach. We first develop a model for the current–potential response of semiconductor micropillar electrodes and validate it using the Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ redox couple under cyclic voltammetry. The model reproduces the main trends observed for SiMPs with different interpillar spacings, and help elucidating its origin. We then extend the analysis to IVP and quantify how pulse parameters (cycle time) and structural parameters (interpillar distance) govern the electrochemical conversion efficiency. Operation under IVP is found to be more effective than under CVP (Constant Voltage Perturbation) for all cycle times studied, with microstructuring further amplifying this advantage. Under near optimal conditions IVP converts up to 14 times more electroactive species than CVP. Overall, this work provides a general, theory-based framework for understanding and optimising IVP in microstructured semiconductor electrodes, laying the groundwork for extension to more complex and catalytically relevant reactions.