Boosting photocatalytic nitrogen reduction to ammonia by dual defective -C N and K-doping sites on graphitic carbon nitride nanorod arrays

Bi-defective g-C 3 N 4 (K and -C N) nanorod arrays with favorable light absorption through multiple light scattering/reflections were designed for photocatalytic N 2 reduction. The highest record of NH 3 production, 23.5 mmol/(h·g cat ), was achieved when dual defects are present at the nanoarrays without any cocatalysts, which is about two orders higher than its counterpart. The N 2 reduction rate is proportional to -C N, unveiling its role as active sites. Its synergistic effect with K was observed. Theoretical calculations support that -C N site is crucial to N 2 activation by donating electrons, while cation like K center traps electrons. Consequently, modification with such dual defects in conjunction with nanoarray configuration creates a favorable electron-dominated structure to overcome the energy barrier for activating inert nitrogen, enhancing charge separation and light absorption effectively. The present work underlines the impetus of defects engineering and nanoarray configuration for the rational design of active photocatalysts for efficient N 2 fixation. The photocatalytic nitrogen fixation activity (23.5 mmol. h −1 . g cat. −1 ) of bi-defective g-C 3 N 4 nanorod arrays outperforms other photocatalysts previously. Our results demonstrated that the dual defects -C N and K take synergistic roles on light-favorable 1D g-C 3 N 4 , resulting in effective N 2 activation, enhanced charge separation, and light absorption. • The morphology of the g-C 3 N 4 is engineered to orderly nanorod arrays. • Dual defective sites (K and -C N) play a synergistic role in photocatalytic N 2 reduction. • Excellent NH 3 yield driven by photocatalysis is achieved under mild conditions.