Electronic Supporting Information

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1 Electronic Supporting Information Enhancing photocatalytic activity of graphitic carbon nitride by co-doping with P and C for efficient hydrogen generation Hao Wang, a Bo Wang, a Yaru Bian, a Liming Dai a,b,* BUCT-CWRU International Joint Laboratory, State Key Laboratory of Organic-Inorganic Composites, Center for Soft Matter Science and Engineering, College of Energy, Beijing University of Chemical Technology, Beijing, China. Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, Euclid Avenue, Cleveland, Ohio, USA Corresponding Author: liming.dai@case.edu. 1

2 Supporting information 1. Calculation details of H 2 -generation rate and apparent quantum efficiency (AQE) H 2 -generation rate was calculated according Equation (S1): = (S1) where ω vol is volume fraction obtained directly from detective results of gas chromatography, V fla (L) is the H 2 volume in pyrex flask, t (h) is irradiation time, m (g) is quality of photocatalysts and (L mol -1 ) is standard molar volume of gases.. Using AQE as the represent of photocatalytic activity of photocatalyst can effectively avoid the difference of light source and other testing conditions. The AQE value was calculated according to the following equations: AQE= h 2 h 100% = 2 h 100% (S2) where (mol) is the amount of evolved H 2 during the irradiation time t (s) under the monochromatic light, h (J s) is Planck s constant, c (m s -1 ) is the speed of light, P (W cm -2 ) is the average power density of incident light, A (cm 2 ) is the irradiated cross-sectional area, and (m) is the wavelength of incident monochromatic light. The AQE of CPCN-1* was measured under 420 nm monochromatic light irradiation for 10h (36000s). The intensity of incident light was measured to be 28.0 mw cm -2 by irradiatometer. The irradiated cross-sectional area was 6.3 cm 2. The 2

3 photocatalytic H 2 -generation rate of CPCN-1* irradiated at 420 nm monochromatic light is 24.6 µmol h -1. Based on the above data, Equation S1 gave a value of 2.14% for the AQE of CPCN-1*. 2. CPCN-X Figure S1 shows the XRD pattern of CPCN-X (X= 0.5, 0.75, 1.00, 1.25, 1.5). Obviously, all the samples show typical g-c3n4 pattern with two peaks at and 27.41, which stands for (100) and (002) crystal face, respectively. Proper crystallinity is a very important property of high performance photocatalyst. Furthermore, we investigated the photocatalytic activity of CPCN-X (X= 0.5, 0.75, 1.00, 1.25, 1.5). As shown in Figure S9, CPCN-1 with proper crystallinity and doping concentration showed the highest H 2 -generation rate, so we chose CPCN-1 as for the subsequent hydrothermal post-treatment to produce CPCN-1*. 3. Stability test of 20-cycle of CPCN-1* The test condition in the first 3-cycle is the same to that in Photocatalytic H2 evolution measurement. Before the forth cycle measurement, the solution was centrifuged to collect the photocatalyst. The obtained photocatalyt was dried in the oven at 80 after flushed with plenty of water. Every four cycles, the procedure was repeated once. 3

4 Figure S1. XRD pattern of CPCN-X (X=0.5, 0.75, 1, 1.25, 1.5). Figure S2. FT-IR spectra of CN, CN*, CPCN-1 and CPCN-1*. 4

5 Figure S3. XPS spectra of (a) CN, (b) CN*, (c) CPCN-1 and (d) CPCN-1*, and all the composition ratios insert into pictures are atomic percentage. 5

6 Figure S4. (a) SEM, mapping pictures and mapping data (b) C, (c) N, (d) O and (e) P of CPCN-1. 6

7 Figure S5. SEM images of (a) CN, (b) CN* and (C) CPCN-1. Figure S6. TEM images of (a) CN, (b) CN*, (C) CPCN-1 and (d) CPCN-1*. 7

8 Figure S7. Mott-Schottky plots of (a) CN, (b) CN*, (C) CPCN-1 and (d) CPCN-1* in 0.2 M Na 2 SO 4 solution. 8

9 Figure S8: EIS data of CN, CN*, CPCN-1 and CPCN-1* electrodes in 0.2 M Na 2 SO 4 aqueous solution, with the insert displaying of equivalent circuit. 9

10 Figure S9. Photocatalytic activity of CN and CPCN-X (X=0. 5, 0.75, 1, 1.25, 1.5) for H2 production using 20 vol. % TEOA aqueous solution as a sacrificial reagent under visible-light irradiation (λ 420 nm, 300 W Xe lamp). 10

11 Figure S10. Time course of photocatalytic H 2 -production from CPCN-1* of 20-cycle. 11

12 Figure S11. The XRD pattern (a), SEM (b) and TEM (C) pictures, XPS deconvoluted spectra of C1s (d), N1s (e), P2p (f), and (g) XPS spectrum of C, N, O, P after 20 cycles stability test. 12

13 Table S1. Comparison of the CPCN-1* performance with reported photocatalysts. Photocatalyst Cocatalyst Reactant solution PDMA/g-C 3 N 4 Na + /g-c 3 N 4 g-c 3 N 4 nanospheres g-c 3 N 4 /MgFe 3 O 4 I-doped g-c 3 N 4 I-doped g-c 3 N 4 nanosheets P-doped g-c 3 N 4 nanosheets g-c 3 N 4 nanosheets P-doped g-c 3 N 4 tubes CPCN-1* Pt (1 wt. Pt (1 wt. Pt (3 wt. Pt (1 wt. Pt (3 wt. Pt (3 wt. Pt (1 wt. Pt (3 wt. Pt (1 wt. Pt (1 wt. and sacrificial agent 400 ml of methanol (10 vol. AQE ( at 420 nm H 2 -generatio n rate (µmol g -1 h -1 ) (20.6μmol h -1 ) 100 ml of water ml of TEOA (15 wt. 100 ml of TEOA (10 wt. 100 ml of TEOA (10 wt. 100 ml of TEOA (10 wt. 100 ml of TEOA (20 wt. 100 ml of TEOA (10 wt. 100 ml of methanol (20 wt. 100 ml of TEOA (31.5 µmol h -1 ) (1.8 µmol h -1 ) 1.8* (30.09 µmol h -1 ) (38 µmol h -1 ) (44.5 µmol h -1 ) (93 µmol h -1 ) (67 µmol h -1 ) (20 wt. work AQE:apparent quantum effiency; PMDA: pyromellitic dianhydride; the H 2 -generation rate in parantheses was directly cited from literature, which was divided by the mass of the catalyst used to give the value in (µmol g -1 h -1 ); AQE* was measured with a 420-nm monochromatic light while the H 2 -generation rate (74.65 µmol h -1 / 0.05 g =1493 µmol g -1 h -1, cf. Fig. 4c) was obtained over nm irradiation. Also, light intensities for these two processes were different, 28.0 mw cm -2 for 24.6 µmol h -1, 88.0 mw cm -2 for 1493 µmol g -1 h -1. Ref This 13

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