Multi-material filaments for 3D printing of photoelectrocatalytic carbon nitride composites

3D printing of conductive structures via fused deposition modelling has emerged as a mainstream manufacturing technique for electrochemical devices owing to the affordability and availability of thermoplastic-carbon-based filaments. On the current market, the existing filaments are limited in terms of their electrical conductivity and functionality. To address this, the development of multi-material filaments incorporating additional functional materials along with conductive carbons strategically produces 3D-printed electrodes with enhanced functionalities. In parallel, filament fabrication allows for precise control over the material composition and properties, such as chemical, thermal, and mechanical properties of the filament. In this work, we explored the fabrication of a multi-material filament combining photocatalytic carbon nitride, C3N4, and conductive carbon nanotubes, CNTs. Our C3N4-CNTs electrodes 3D-printed from it outperformed CNTs electrodes in hydrogen evolution and photocatalytic degradation of an organic dye. Our findings suggest that multi-material filaments may transcend the current filament-extrusion printing technique and expand its potential beyond electrochemistry.