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Caption : fig. s1. (a) xrd patterns and (b) tem image of the prepared cucl precipitates. (c) cu element and (d) cl element mapping images of cucl precipitates.

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Caption : fig. s2. (a) uv-vis absorption spectra, (b) xrd patterns (c) xps patterns and (d) sem images of cu/cuo when ratio of cu2+/cl- was 2:0.

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Caption : fig. s3. (a) uv-vis absorption spectrum, (b) xrd patterns and (c) xps patterns of the sample when ratio of cu2+/cl- was 2:1. the inset in (a) was the photograph of the solution of the prepared sample.

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Caption : fig. s4. (a) tem image and (b) saed pattern of cu2o-nps prepared without addition of pam. (c) hr-tem image and fft image of the selected area (yellow box) in (a), (d) xps pattern of cu2o-nps.

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Caption : fig. s5. (a)uv-vis absorption spectra of indophenol assays kept with different concentrations of nh4+. (b) a calibration curve used to estimate the concentrations of nh4+ ions.

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Caption :  fig. s6. uv-vis absorption spectra of indophenol assays kept with different times during photocatalytic nitrogen reduction for 2 h under visible light irradiation (λ > 420 nm) at room temperature. (a) cu2o-nps, (b) cu2o-mc-s and (c) cu2o-mc-p.

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Caption : fig. s7. uv-vis absorption spectra of indophenol assays kept with different times during photocatalytic nitrogen reduction for 2 h under 395 nm irradiation at room temperature. (a) cu2o-nps, (b) cu2o-mc-s and (c) cu2o-mc-p.

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Caption : fig. s8. mass spectra of the indophenol products obtained by reaction of phenol with ammonia generated from photocatalytic 14n2 or 15n2 reduction. the inset showed the chemical structure of the indophenol product, with m/z = 198 (14n) and m/z = 199 (15n).