Nanoscale lightning rod effect in 3D carbon nitride nanoneedle: Enhanced charge collection and separation for efficient photocatalysis

Polymeric materials are promising photocatalysts for clean energy (e.g. hydrogen) production, however their catalytic performances are largely restricted to the low charge mobility and sluggish electron-hole separation efficiency. Herein, we propose a novel three dimensional (3D) branched carbon nitride integrated by one dimensional (1D) nanoneedles (3DBC-C3N4-N) to overcome this obstacle. We verify that the integrated crystalline nanoneedles with high curvature tips could induce a lightning rod effect property to accelerate charge transfer and separation by guiding electron migration along the sharp tip direction. Both 3D finite-difference time-domain (FDTD) calculation and experimental results reveal that the high curvature crystalline tip can intensify the local electric intensity by concentrating the photogenerated electrons around the tip area, therefore significantly enhance electron-hole separation. As a result, the 3DBC-C3N4-N exhibits excellent visible light (lambda > 420 nm) photocatalytic H2O2 production as well as H2 evolution performance with obvious bubbles bubble out from the surface of catalyst and a notable apparent quantum efficiency (AQE) of 26% at 420 nm, higher than most reported polymeric materials. The innovative lightning rod effect strategy described here shows great potential to manipulate charge transfer and separation process for achieving efficient solar energy conversion. (C) 2019 Elsevier Inc. All rights reserved.