Wood-Inspired Binder Enabled Vertical 3D Printing of g-C3N4/CNT Arrays for Highly Efficient Photoelectrochemical Hydrogen Evolution

2D nanomaterials are very attractive for photoelectrochemical applications due to their ultra-thin structure, excellent physicochemical properties of large surface-area-to-volume ratios, and the resulting abundant active sites and high charge transport capacity. However, the application of commonly used 2D nanomaterials with disordered-stacking is always limited by high photoelectrode tortuosity, few surface-active sites, and low mass transfer efficiency. Herein, inspired by wood structures, a vertical 3D printing strategy is developed to rapidly build vertically aligned and hierarchically porous graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) arrays by using lignin as a binder for efficient photoelectrochemical hydrogen evolution. Arising from the directional electron transport and multiple light scattering in the out-of-plane aligned and porous architecture, the resulting g-C3N4/CNT arrays display an outstanding hydrogen evolution performance, with the hydrogen yield up to 4.36 mu mol (cm(-2) h(-1)) at a bias of -0.5 V versus RHE, 12.7 and 41.6 times higher than traditional thick g-C3N4/CNT and g-C3N4 films, respectively. Moreover, this 3D printed structure can overcome the agglomeration problem of the commonly used g-C3N4 with powder configuration and shows desirable recyclability and stability. This facile and scalable vertical 3D printing strategy will open a new avenue to highly enhance the photoelectrochemical performance of 2D nanomaterials for sustainably production of clean energy.

Automated summary

Inspired by wood structures, a vertical 3D printing strategy was developed to fabricate vertically aligned and hierarchically porous g-C3N4/CNT arrays for efficient photoelectrochemical hydrogen evolution. The resulting arrays exhibited excellent hydrogen evolution performance, overcoming aggregation issues of traditional g-C3N4, and showing high potential for practical applications.