A Graphitic‐C 3 N 4 “Seaweed” Architecture for Enhanced Hydrogen Evolution

A seaweed‐like graphitic‐C 3 N 4 (g‐C 3 N 4 “seaweed”) architecture has been prepared by direct calcination of the freeze‐drying‐assembled, hydrothermally treated dicyandiamide fiber network. The seaweed network of mesoporous g‐C 3 N 4 nanofibers is favorable for light harvesting, charge separation and utilization of active sites, and has highly efficient photocatalytic behavior for water splitting. It exhibits a high hydrogen‐evolution rate of 9900 μmol h −1  g −1 (thirty times higher than that of its g‐C 3 N 4 bulk counterpart), and a remarkable apparent quantum efficiency of 7.8 % at 420 nm, better than most of the g‐C 3 N 4 nanostructures reported. This work presents a very simple method for designing and developing high‐performance catalysts for hydrogen evolution.