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. Solar-Driven Cellulose Photorefining
into Arabinose over Oxygen-Doped Carbon
Nitride
Jiu Wang, Qi Zhao, Pawan Kumar, Heng Zhao*, Liquan Jing, Devis Di Tommaso, Rachel Crespo-Otero, Md Golam Kibria* and Jinguang
Hu*
ACS Catalysis 2024
DOI:
https://doi.org/10.1021/acscatal.3c06046

2. Figure 1. (a) Synthetic process for
oxygen-doped CN through one-step
solvothermal synthesis. (b) FESEM
image, (c) TEM image, and (d) HAADF-
STEM image of OCN–OH with relevant
elemental mappings. The colors of red,
green, and blue represent the elemental
components of C, N, and O,
respectively.

3. Figure 2. (a) FTIR
spectra, (b) UV–Vis
DRS, (c) TRPL spectra,
and (d) EPR spectra of
DCN and OCN–OH.
Calculated DOS of (e)
DCN and (f) OCN–OH.
HOMO and LUMO
distributions of (g)
DCN and (h) OCN–OH,
respectively.

4. Figure 3. High-resolution XPS
spectra of (a) C 1s, (b) N 1s,
and (c) O 1s of DCN and OCN–
OH. (d) Solid-state 13C NMR
spectra of DCN and OCN–OH.
XANES spectra of the (e) C K-
edge and (f) N K-edge for DCN
and OCN–OH.

5. Figure 4. (a) Glucose
conversion and
corresponding arabinose
selectivity of OCN–OH
upon 6-h irradiation
under air atmosphere.
(b) The recyclability
of OCN–OH for glucose
photoreforming into
arabinose during three
cycles for 18 h. (c)
Glucose conversion
under O2 atmosphere,
and corresponding (d)
products selectivity,
and (e) carbon balance
for glucose
photoreforming over
OCN–OH. (f) Scavenger
experiments of OCN–OH
with the addition of
BQ, TBA, and EDTA-2Na.
(g) ESR spectra of CPH-
h+ under N2, (h) DMPO-
•O2– and (i) DMPO-•OH
for OCN–OH. Reaction
conditions: 10 mg of
photocatalyst, 10 mL of
2g/L glucose solution
(pH ∼ 7), air or O2,
and 300 W xenon lamp.