Microfluidic-enhanced 3-D photoanodes with free interfacial energy barrier for photoelectrochemical applications

•We hypothized the design of 3-D microfluidic-enhanced photoelectrochemical system.•1-D ZnO was assembled onto carbon cloth to construct 3-D flow-through photoanodes.•Heterostructures with free interfacial barrier for electron transfer were obtained.•Flow-through photoanode exhibited superior reaction kinetics than planar photoanode.•Fluid dynamics simulation confirmed the improved mass transfer in flow-through mode.