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1 SUPPRTING INFRMATIN Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface xygen Vacancies of Titanium Dioxide Hiroaki Hirakawa, Masaki Hashimoto, Yasuhiro Shiraishi,*,, and Takayuki Hirai Research Center for Solar Energy Chemistry, and Division of Chemical Engineering, Graduate School of Engineering Science, saka University, Toyonaka , Japan PREST, JST, Saitama 332-2, Japan CNTENTS page Figure S. XRD patterns of the catalysts... S2 Figure S2. Relationship between activity and morphology of the catalysts... S3 Figure S3. Time profiles for NH3 formation on the respective Ti2... S3 Figure S4. Time profiles for photocatalytic N2 reduction with 2-PrH... S4 Figure S5. Time profiles for photocatalytic water oxidation with NaI3... S4 Figure S6. Result for photocatalytic NH3 decomposition... S5 Figure S7. Light emission spectra for high-pressure Hg lamp and simulated sunlight... S5 Figure S8. DRIFT spectra of nitrobenzene adsorbed on the catalysts... S6 Figure S9. DRIFT spectra of N2 adsorbed on JRC-TI-6... S7 Figure S. DRIFT spectra of N2 adsorbed on the respective catalysts... S7 Figure S. UV-vis spectra of the metal-loaded catalysts... S8 Table S. Results for photocatalytic NH3 formation under various reaction conditions... S8 S

2 JRC-TI- () ST-2 (2) ST- (3) NS-5 (4) Wako rutile (5) PT- (6) P25 (7) JRC-TI-6 (8) [] anatase [] [4] [2] [] [2] rutile / deg Figure S. XRD patterns of respective Ti2 particles and standard patterns of anatase (JCPDS 2-272) and rutile (JCPDS 2-276). S2

3 a.8 8 b v f / M h S BET / m 2 g v f / M h d P / nm Figure S2. Relationship between the rate of NH3 formation (vf) versus (a) BET surface area (SBET) and (b) particle size (dp) of the respective Ti2. JRC-TI-6 (8) 3 NH 3 (NH 4 + ) formed / M 2 PT- (6) ST-2 (2) ST- (3) t / h NS-5 (4) JRC-TI- () Wako rutile (5) Figure S3. Change in the amount of NH3 formed by photoirradiation with the respective Ti2 in pure water under N2 bubbling. Reaction conditions: water (2 ml), catalyst (2 mg, 2.5 mmol), N2 (.3 L min ), temperature (33 K), λ >28 nm (intensity at nm: 35 W m 2 ). S3

4 5 NH 3 formed / M 4 2 PrH/water (/9 w/w) 3 2 water t / h Figure S4. Result for reduction of N2 on JRC-TI-6 (sample 8) in (black) pure water or (white) 2-PrH/water (9/ w/w) mixture under UV irradiation ( >3 nm). The photoreactions were carried out under N2 bubbling (.3 L min ). 3 ph. 2 formed / mol 2 ph 7. ph t / h Figure S5. Time-dependent change in the amounts of 2 formed by photoirradiation ( >28 nm) of JRC-TI-6 (catalyst 8). The reactions were carried out in buffered. M potassium phosphate solutions with.5 M NaI3 as a sacrificial electron acceptor under Ar atmosphere. S4

5 ph 4. ph 7. C/C.5 ph t / h Figure S6. Results for NH3 photodecomposition on JRC-TI-6 (catalyst 8) under photoirradiation ( >28 nm). The reactions were carried out in buffered. M potassium phosphate solutions with.5 mm NH3 under air bubbling (.3 L min ). A JRC TI 6 (sample 8) High pressure Hg lamp Simulated AM.5G sunlight / nm Spectral irradiance / W cm 2 / nm Figure S7. Absorption spectrum of JRC-TI-6 (catalyst 8), and light emission spectra for high-pressure Hg lamp and simulated AM.5G sunlight. S5

6 H Ti 4+ Ti 4+ H N JRC-TI- () ST-2 (2) ST- (3) NS-5 (4) Wako rutile (5) asym 522 sym 346 Ti 4+ Ti 3+ Ti 3+ N Ti 4+ Ti 4+ Ti 4+ Ti4+ Ti4+ PT- (6) F(R ).3 JRC-TI-6 (8) Ru/JRC-TI-6 (8) / cm - Figure S8. DRIFT spectra of nitrobenzene adsorbed onto the respective Ti2 particles in the gas phase at 33 K. The spectra were measured as follows: respective Ti2 (5 mg) were placed in a DR cell and evacuated (.9 Pa) at 423 K for 3 h. Nitrobenzene (6.5 µmol) was introduced to the cell at 33 K and left for h. The cell was then evacuated (.9 Pa) for h to remove the physically adsorbed nitrobenzene. The absolute amount of nitrobenzene adsorbed onto the surface was calculated based on the equilibrium adsorption amount of nitrobenzene (Shiraishi, Y.; Hirakawa, H.; Togawa, Y.; Sugano, Y.; Ichikawa, S.; Hirai, T. ACS Catal. 23, 3, ). The shoulder peaks observed on JRC-TI-6 (8) indicate that some nitrobenzene molecules with different N length are adsorbed on the surface. As shown in Table (manuscript), the size of JRC-TI-6 particles are small and they may have a rough surface. The steric hindrance by the rough surface may affect the adsorption of nitrobenzene and creates these shoulder peaks. S6

7 JRC-TI-6 (8) + N 2 N=N 236 cm - F(R ). dark 4 min / cm - Figure S9. DRIFT spectra of N2 adsorbed on JRC-TI-6 (8) at K. Measurement was started in the dark after injection of N2 (42 μmol) to the cell containing the catalyst. The spectra are identical to those in Figure 2a (manuscript). a. JRC-TI-6 (8) + N 2 Ti-H 359 cm - N-H 3372 cm - N-H 336 cm - dark 4 min dark 4 min b. JRC-TI- () + N 2 F(R ) / cm - Figure S. DRIFT spectra of N2 adsorbed on (a) JRC-TI-6 (8) and (b) JRC-TI- () at K. Measurement was started in the dark after injection of N2 (42 μmol) to the cell containing the catalyst. S7

8 3 JRC TI 6 (8) 2 Pd/JRC TI 6 (8) F(R ) Pt/JRC TI 6 (8) Ru/JRC TI 6 (8) / nm Figure S. Diffuse reflectance UV-vis spectra of the metal-loaded catalysts. Table S. Results for photocatalytic NH3 production from water and N2. a entry catalyst light water N2 NH3 (NH4 + ) NTi / M / mol g b JRC-TI-6 (8) JRC-TI-6 (8) + + <. 3 JRC-TI-6 (8) + c + <. 4 JRC-TI-6 (8) + + d <. 5 none <. 6 Ru/JRC-TI-6 (8) e Pt/JRC-TI-6 (8) e Pd/JRC-TI-6 (8) e H2-treated JRC-TI-6 (8) f a Reaction conditions: water (2 ml), catalyst (2 mg), N2 (.3 L min ), temperature (33 K), λ >28 nm (intensity at nm: 35 W m 2 ), time (24 h). b The number of surface Ti 3+ atoms on Ti2 determined by DRIFT analysis with nitrobenzene as a probe molecule (Shiraishi, Y.; Hirakawa, H.; Togawa, Y.; Sugano, Y.; Ichikawa, S.; Hirai, T. ACS Catal. 23, 3, ). c Performed in MeCN. d Performed under Ar bubbling. e The amount of metal loaded [= M/Ti2 ] is.5 wt %. f Prepared by H2 reduction of catalyst (8) at 973 K. S8