Photocatalytic overall water splitting by conjugated semiconductors with crystalline poly(triazine imide) frameworks

In this work, we apply a carbon nitride semiconductor with a crystalline poly(triazine imide) (PTI) frameworks to photocatalytic overall water splitting.

Cocatalysts deposition. The Co or Pt cocatalyst was loaded on the photocatalyst surface by in situ photodeposition method. Briefly, 100 mg photocatalyst powder was dispersed in deionized water (100 mL) contained 10% vol (10 mL) methanol (MeOH) as the sacrificial agent. A certain amounts of CoCl 2 (3 wt%, 6 wt%, 9 wt%, 12 wt%, based on Co atoms) or H 2 PtCl 6 (1 wt%, based on Pt atoms) were added into the solution. After 1 hour photodeposition using full arc irradiation of 300W lamp, the photocatalyst was filtration and washed with deionized water several times. Then the photocatalyst was dried at 60 o C for 4 hours.
The Co and Pt cocatalysts were loaded on the photocatalyst surface by in situ photodeposition method. Briefly, 100 mg photocatalyst powder was dispersed in deionized water (100 mL) contained 10% vol (10 mL) MeOH as the sacrificial agent. A certain amounts of CoCl 2 (3 wt%, 6 Electronic Supplementary Material (ESI) for Chemical Science. This journal is © The Royal Society of Chemistry 2017 wt%, 9 wt%, 12 wt%, based on Co atoms) were added into the solution. After 1 hour photodeposition using full arc irradiation of 300W lamp, the photocatalyst was filtration and washed with deionized water several times. Then, the photocatalyst powder was dispersed in deionized water (100 mL) contained 10% vol (10 mL) methanol as the sacrificial agent. A certain amounts of H 2 PtCl 6 (1 wt%, based on Pt atoms) were added into the solution. After 1 hour photodeposition using full arc irradiation of 300W lamp, the photocatalyst was filtration and washed with deionized water several times. Then the photocatalyst was dried at 60 o C for 4 hours.
The PtO x /PTI·HCl was synthesized by a typical immersion strategy followed by thermal treatment in the air. Typically, 200 mg of PTI·HCl powders was immersed in 5 mL of deionized water water followed ultrasonication for 5 minutes. Then, a certain amounts of H 2 PtCl 6 (1 wt%, based on Pt atoms) were added into the solution. The final resultant sample was obtained after evaporation and thermal treated in muffle furnace at 300 o C for 1 h.
Photocatalytic activity test. The reactions were carried out in a Pyrex top-irradiation reaction vessel connected to a glass closed gas system. The hydrogen production was performed by dispersing 100 mg of photocatalyst powder in pure water (100 mL) contained 10% vol (10 mL) MeOH as the sacrificial agent. The oxygen production was performed by dispersing 100 mg of photocatalyst powder in pure water (100 mL) contained 0.01 M AgNO 3 as the sacrificial agent and 0.2g La 2 O 3 as a pH buffer agent. The overall water splitting was carried out by dispersing 100 mg of photocatalyst powder in pure water (100 mL). The reaction solution was evacuated several times to completely remove the air prior to full spectrum irradiation of 300 W Xe lamp. The temperature of the reaction solution was maintained at room temperature using a flow of cooling water during the reaction. The evolved gases were analyzed by a gas chromatography equipped with a thermal conductive detector (TCD) and a 5A molecular sieve column, using argon as the carrier gas.
The apparent quantum yield (AQY) for the overall water splitting was determined by replacing the Xe lamp with LEDs equipped with different band-pass filters. The irradiation area was 9 cm 2 . The total intensity irradiation was measured by averaging 10 points in the irradiation area. For example, the average intensity was 6.8 mW cm -2 for the 380nm monochromatic light (ILT 950 spectroradiometer). The AQY was calculated as follow: AQY=N e /N p ×100%=2M/N p ×100% where N e is the amount of reaction electrons, N p is the incident photons, M is the amount of H 2 molecules. Theoretical calculations. The periodic DFT calculations were performed using pure PBE 2 XC functional and the plane wave basis sets 3 as implemented in the Vienna ab initio simulation package (VASP). [4][5][6] The C s 2 p 2 , N s 2 p 3 were treated as valence electrons. The cutoff energy for the plane-wave basis set was 550 eV. The geometry optimizations were performed using the conjugate gradient technique, until the total energies converged to 10 -4 eV and the Hellmann-Feynman forces on the atoms were less than 0.01 eV Å -1 . For band calculations, the high symmetry k-paths were obtained from the literature. 7 The single layer model of melon-based CN was used in present calculation. Although some programs have been developed, the theoretical calculation of random structures remains challenging. Therefore, we only constructed the backbone of PTI·HCl with single layer as the preliminary model. In this regard, further investigation is required to reveal the influence of those ions on the electronic properties and bandstructure of PTI·HCl.    (f) Figure S4. XPS results of (a) the survey spectrum and high-resolution spectra of (b) C 1s, (c) N 1s, (d) Cl 2p, (e) Li 1s and (f) K 2p for PTI·HCl.