Dimensionality-engineered electron channels for directional acceleration of 1,4-NADH-dependent photoenzymatic CO2-to-liquid fuels

Featuring multiple electron transfer and adequate hydride supply, the 3D polymer photocatalyst achieves 90.8 % activity and 99.2 % selectivity for photocatalytic regeneration of 1,4-NADH that boosts the cascade enzymatic reduction of CO 2 to ethanol by 2.0-fold. Efficient and selective regeneration of enzymatically active 1,4-NADH from NAD + is pivotal for accelerating photoenzymatic CO 2 conversion. However, constructing photocatalysts that sustain continuous electron flow and provide sufficient hydride supply remains a major challenge. Herein, we report a rhodium-coordinated three-dimensional conjugated polymer (3D-Bpy-Rh) photocatalyst featuring multiple electron channels, designed through dimensionality engineering and incorporation of hydride-forming active centers. Such a 3D structure promotes rapid charge separation and multidimensional electron migration, while facilitating trapped-electron release to Rh centers for accelerated electron transfer. As a result, 3D-Bpy-Rh achieves a visible-light driven NADH regeneration efficiency of 90.8 % with 99.2 % selectivity toward 1,4-NADH, surpassing state-of-the-art photocatalysts. Furthermore, the mechanism between the electron reduction capability of the photocatalyst and the selective formation of 1,4-NADH was elucidated, combining transient absorption spectroscopy analysis and DFT calculations. When integrated into photoenzymatic systems, this photocatalyst enhances CO 2 conversion, boosting methanol and ethanol yields by 5.2- and 2.0-fold, respectively. These results highlighted the potential of dimensionality-engineered photocatalysts for selective 1,4-NADH regeneration and efficient photoenzymatic fuel synthesis.