DIW 3D printing of well-interconnected hierarchically porous microlattice for ultrasensitive photoelectrochemical sensing

Endowing channel-interconnected photoelectrode with prominent light-absorbing and analyte-trapping is pivotal but challenging for implementing high-performance photoelectrochemical sensing system. Herein, we demonstrated an effective and controllable direct ink writing (DIW) 3D printing coupled with molecular imprinting technology for consistently fabricating microlattice-shaped photoelectrochemical sensor, with multiscale well-interconnected channels created by accessible alliance of regular macrochannels originated from layer-by-layer assembly of printed filaments and abundant microchannels built by jointing molecule-recognized polyaniline (PANI), photoactive TiO₂ and conductive graphene (G) nanosheets within filaments. The unique structure merit facilitated ready spreading of incident light into the sensor interior, and meanwhile enabled rapid diffusion/infiltration of analytes onto all specificity binding sites situated inside the sensor, thereby allowing light absorbance and analyte adsorption at a high level. As a result, the 3D-printed molecularly imprinted photoelectrochemical sensor displayed impressive monitoring capability for urea, with rapid response, low detection limit (2 μM), wide linear range (10–700 μM), exceptional selectivity and working stability. This work opens up a promising route for architecting advanced photoelectrochemical devices to cater to highly sensitive and selective sensing.