Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2016 Supporting Information 15 Isotopic labeling experiments are carried out as follow. Labeled N2 gas was purchased from Sigma-Aldrich Chemical Company. In the experimental process, reaction mixture was firstly purged with Ar for 30 min to eliminate air and some 15 possible adsorbed ammonia. Then, N2 was passed through the reaction mixture for 30 min. After that, the reactor was sealed and irradiated under visible light. Other 14 experiment conditions were the same as those for N2 photofixation. Indophenol 15 + 15 + method was used to examine the obtained NH4 , owing to the low mass of NH4 for LC-MS studies. The sample for LC-MS analysis was prepared as follows. 0.5 ml of the reaction reacted with 0.1 ml of 1% phenolic solution in 95% ethanol. Then, 0.375 ml of 1% NaClO solution and 0.5 mL of 0.5% sodium nitroprusside solution were added into above solution. MS studies were carried on an Ultimate 3000-TSQ (LCMS-ESI). The simulations were performed using the program package Dmol3. The substrate is modelled by one layer of g-C3N4 separated by a vacuum layer of 12Å. All the atoms in the layer and the N2 molecule are allowed to relax. The Brillouin zones of the supercells were sampled by the Gamma points. Based on the structures of g-C3N4, the g-C3N4 surface with nitrogen atom vacancy was modelled to study the N2 adsorption properties. 12 without irradiation t a c 10 without N g 2 / L / without photocatalyst g m 8 / n o i t a 6 r t n e c n 4 o c + 4 H 2 N 0 0 1 2 3 4 time / h Figure S1. The N2 photofixation ability of CN520 in the absence of irradiation, N2 or photocatalyst. 35 2.0 (a) (b) IM-CN(30) 1.8 IM-CN(30)+DMF 30 t t IM-CN(30)+DMSO IM-CN(30) + AgNO a a 3 c c 1.6 g g / / L L 25 / / 1.4 g g m m / 1.2 / 20 n n o i o 1.0 i t t a a 15 r r t t 0.8 n n e e c c 10 n 0.6 n o o c c + 0.4 + 4 4 5 H H N 0.2 N 0 0.0 0 1 2 3 4 0 1 2 3 4 time / h time / h Figure S2. Nitrogen photofixation ability of IM-CN(30) using AgNO3 as the electron scavenger (a) or in aprotic solvents DMF and DMSO (b). 200 180 CN520 ) P M-CN(20) T 160 S IM-CN(30) g / 3 140 m c ( 120 d e b r 100 o s d 80 a 2 N 60 e m 40 u l o V 20 0.0 0.2 0.4 0.6 0.8 1.0 Rlative pressure (P/P0) Figure S3. N2 adsorption-desorption isotherms of as-prepared CN520, M-CN(20) and IM-CN(30). 1.0 CN520 M-CN(20) 0.8 IM-CN(30) 0.6 0 C / 3.0 C 0.4 2.5 ) 0 2.0 C / C 1.5 ( n 0.2 l - 1.0 0.5 0.0 0.0 0 20 40 60 80 100 120 time / min -40 -20 0 20 40 60 80 100 120 140 time / min Figure S4. The RhB degradation performance over as-prepared CN520, M-CN(20) and IM-CN(30) under visible light. Table S1. Photocatalytic H2 production ability of as-prepared catalysts Catalyst CN520 M-CN(20) IM-CN(30) -1 H2 production (μmol·h ) 0.40 0.52 0.55 The photocatalytic H2 production were performed in an outer-irradiation and air-tight Pyrex glass reactor, connected to a water-cooling system. In a typical run, 0.2 g photocatalyst was suspended in 100 ml deionized water with methanol (10 vol.%, used as the hole scavenger) under stirring. Prior to the photocatalytic reaction, the suspension was purged with Ar gas for 20 min to get rid of O2. A 250 W high- pressure sodium lamp with UV cutoff filter (λ > 420 nm) were used as light source. A continuous magnetic stirrer was applied at the bottom of the reactor in order to keep the photocatalyst particles in suspension status during the whole experiment. The reaction products were analyzed on-line by thermal conductivity detectors on a micro- gas chromatography (Model Agilent P200 Series) equipped with a thermal conductivity detector (TCD) and a stainless steel column (2 m) packed with molecular sieves (5A) at 323 K. Ar was used as the carrier gas at a flow rate of 20 cm3·min-1. All runs were conducted at ambient pressure and 30 C..