Biomass photorefining is a promising strategy to address the energy crisis and transition toward carbon carbon-neutral society. Here, we demonstrate the feasibility of direct cellulose photorefining into arabinose by a rationally designed oxygen-doped polymeric carbon nitride, which generates favorable oxidative species (e.g., O2–, •OH) for selective oxidative reactions at neutral conditions. In addition, we also illustrate the mechanism of the photocatalytic cellulose to arabinose conversion by density functional theory calculations. The oxygen insertion derived from oxidative radicals at the C1 position of glucose within cellulose leads to oxidative cleavage of β-1,4 glycosidic linkages, resulting in the subsequent gluconic acid formation. The following decarboxylation process of gluconic acid via C1–C2 α-scissions, triggered by surface oxygen-doped active sites, generates arabinose and formic acid, respectively. This work not only offers a mechanistic understanding of cellulose photorefining to arabinose but also sets up an example for illuminating the path toward direct cellulose photorefining into value-added bioproducts under mild conditions.

1. 1
Supporting Information
Solar-driven cellulose photorefining into arabinose over oxygen-
doped carbon nitride
Jiu Wang,a,† Qi Zhao,b,† Pawan Kumar,a Heng Zhao,a,d* Liquan Jing,a Devis Di
Tommaso,b Rachel Crespo-Otero,c Md Golam Kibria a,* and Jinguang Hu a,*
a Department of Chemical and Petroleum Engineering, University of Calgary, 2500
University Drive, NW, Calgary, Alberta, T2N 1N4, Canada
b Department of Chemistry Queen Mary University of London, Mile End Road,
London E1 4NS, UK
c Department of Chemistry University College London, 2020 Gordon St., London,
WC1H 0AJ, UK
d Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo,
Zhejiang 315200, China

2. 2
Figure S1. (a) FESEM image and (b) TEM image of DCN.

3. 3
Figure S2. XRD patterns of DCN and OCN-OH.

4. 4
Figure S3. PL spectra of DCN and OCN-OH.

5. 5
Figure S4. (a) Transient photocurrent curves and (b) EIS Nyquist plots of DCN and
OCN-OH.

6. 6
Figure S5. Mott-Schottky plots collected at different frequencies of (a) DCN and (b)
OCN-OH. (c) Band structure of DCN and OCN-OH.

7. 7
Figure S6. The HOMO, LUMO and whole HOMO-LUMO distribution of (a) DCN
and (b) OCN-OH, respectively.

8. 8
Figure S7. HPLC measurements of aqueous solution from cellulose photorefining over
OCN-OH sample upon 24-h irradiation under O2 atmosphere.

9. 9
Figure S8. Glucose conversion and arabinose selectivity of OCN-OH upon 8-h
irradiation under O2 atmosphere.

10. 10
Figure S9. The production of CO during 6-h glucose photoreforming over OCN-OH
under O2 atmosphere.

11. 11
Figure S10. Photograph of the H2O2 test paper measuring the solution before and after
reaction.

12. 12
Figure S11. Gluconic acid conversion and arabinose production of OCN-OH using
gluconic acid as initial substrate upon 6-h photocatalytic reaction.

13. 13
Figure S12. Theoretical oxygen concentration of the photocatalysts in DFT model.

14. 14
Figure S13. Possible reaction pathway for acetic acid production during glucose
photoreforming.

15. 15
Table S1. The fluorescence lifetimes and relative percentage of DCN and OCN-OH.
Sample τav(ns) τ1(ns)
(rel. %)
τ2(ns)
(rel. %)
DCN 9.83 2.76(47.7) 11.4(52.3)
OCN-OH 5.42 1.41(54.9) 6.49(45.1)
Table S2. The elemental analysis of DCN and OCN-OH.
Sample N (%) C (%) H (%) O (%)
DCN 59.72 34.23 2.01 1.64
OCN-OH 43.80 27.54 3.58 16.87
Table S3. Elementary reactions and intermediates on DCN and OCN-OH presenting in
Figure 5e.
Reaction ∆E(eV)
DCN
∆E(eV)
OCN-OH
*+Glucose→Glucose* (Int.1) -0.62 -0.61
O2 +Glucose*→Glucose*+O2*(Int.2) 0.87 0.58
Glucose*+O2*→Gluconolactone*+H2O2*(Int.3) -2.35 -2.48
Gluconolactone*+H2O2*→Gluconolactone*(Int.4)+H2O2↑ 0.66 0.30
Gluconolactone*+H2O → Gluconolactone*+H2O*(Int.5) -0.37 -0.36
Gluconolactone*+H2O*→Gluconic acid*(Int.6) 0.24 -0.38
Gluconic acid*→Arabinose*+HCOOH*(Int.7) -0.18 -0.35