Supplementary information for：

Artificial photosynthesis of oxalate and oxalate-based polymer by a photovoltaic reactor

Guangzai Nong1, Shan Chen1, Yuanjin Xu3, Lijie Huang1, Qingsong Zou1, Shiqiang Li2, Haitao Mo1 , Pingchuan Zhu3, Weijian Cen3and Shuangfei Wang2*

1Center for Sugar Engineering and Technology Research, Guangxi University，Nanning, Guangxi，530004，P.R.China；

2Institute of Light Industry and Food Engineering，Guangxi University，Nanning, Guangxi，530004，P.R.China；

3State key laboratory for conservation and utilization of subtropical agro-bioresources, Guangxi University，Nanning, Guangxi，530004，P.R.China.

1.  The polymer

S. Fig. 1 was the picture of the polymer, from that picture; the polymer was seen as a transparent or translucent solid body.

S. Fig. 2 The picture of the polymer

2. Evidence of H2C2O4

The concentration of H2C2O4 was tested by Guangxi center for analysis and test research. Sample of 100 ml solution was obtained by diluted 50ml of the produced solution with water. The tested results showed the concentration of (H2C2O4) was 866 mg/100ml.

3. Evidences of GPC

The evidences of GPC are shown in S. Fig 2, S. Fig 3 and S. Fig 4.

S. Fig. 2 The report on the absorption areas of peak in 11.9 and 19.04 minute.

S. Fig 2 shows that the substrate of 11.9 is the main composition of the neutral solid products, which account for 86.6% of the total absorption area. Anther substrate of 19.04 account for 13.4% of the total absorption area.

S. Fig. 3 The report on the molecular weight of peak in 11.9 minute

S. Fig. 3 shows that the molecular mass of peak in 11.9 minute is 2.37×105 g/mol (Mw).

S. Fig. 4 The report on the molecular weight of peak in 19.04 minute

S. Fig. 4 shows that the molecular weight of peak in 19.04 minute is 191.56 g/mol (Mw) by GPC.

4.  Evidences for existence of CH2 and CH in the polymer molecule

S. Fig 5 is the original spectrums of DEPT C135°, in where the up-right peak at δ 72.21 is the group of CH2, and the down-right peak at δ 62.69 is the group of CH. Therefore, the existence of CH2 and CH is conformed.

S. Fig 5 The original DEPT C135° spectrum

5. Analysis of the spectrum of HSQC

S. Fig 6 is the original spectrums of HSQC. Analyzed by the software of Mestre-C, it discovered the follow facts. (1) At the range of δ 0 – 2.8, there is not any connection between H and C. therefore; the peak δ 2.007 of 1H NMR can be regarded as an interference peak. (2) At the range of δ 7.0 – 9.0, there is not any connection between H and C, and the peak δ 8.544 of 1H NMR are in the range of OH group (δ3.0-9.0). Therefore, the peak can be assigned to OH group; (3) the CH group and CH2 group overlapped at the line of δ 3.892. Therefore, the peak area included the H number of CH group and a minority of the H number of the CH2 group.

S. Fig 6 The original HSQC spectrum

6.  Evidences for existence of glyoxal in the produced solution

The GC results are shown in S. Fig. 7 and 8. S. Fig. 7 is the report on the HPGC spectrum of standard single glyoxal benzene solution. In where the single glyoxal is located at retention time of 3.766 minute and its peak area is 4584.47 PA.S. Fig. 8 is the report on the HPGC spectrum of the sample of benzene extraction. In where the peak located at retention time of 3.684 minute with area of 567.20 PA.S, is regarded as product of single glyoxal produced during artificial photosynthesis. The two reports indicate the existence of glyoxal.

S. Fig. 7 The report on the HPGC spectrum of standard single glyoxal benzene solution.

S. Fig. 8 The report on the HPGC spectrum of the sample of benzene extraction

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