Scalable Photocatalytic Microlens Arrays Imprinted in Carbon Dot‐Based Photoresists

ABSTRACT Regulated photocatalysis by integration of optics presents a powerful avenue to enable high‐efficiency energy conversion under the fluctuating conditions of natural sunlight. Yet inefficiency arises when the concentrated photonic energy and the nanoscale catalytic sites mismatch in dimensions. To address this, a hybrid photocatalytic microlens array is designed and manufactured with scalable imprinting technology. Photocatalytic carbon dots (CDs) are uniformly integrated into the imprinted plano‐convex microlens array. The convex microlens focuses the incident light onto the flat back surface, where the photocatalytic reactions take place at the nanoscale CD sites. As a proof‐of‐concept, we verify the structural and functional synergy of the photocatalytic microlens arrays via the degradation of Eosin Y under weak light, achieving a reduction of 64% on the illumination lower threshold to initiate photochemical reactions. Further integration of the photocatalytic microlens arrays with a continuous‐flow photochemical reactor results in a 78 fold increase in pollutant removal efficiency compared to batch conditions. The scalability, flexibility, and superior photocatalytic performance of the CD‐based microlens array not only present a viable solution for environmental applications like water treatment, but also pave a hybrid pathway for the design of high‐efficiency photochemical reactors.