2 research outputs found
Construction of Monoatomic-Modified Defective Ti<sup>4+</sup><sub>α</sub>Ti<sup>3+</sup><sub>1‑α</sub>O<sub>2−δ</sub> Nanofibers for Photocatalytic Oxidation of HMF to Valuable Chemicals
Efficiently upgrading 5-hydroxymethylfurfural
(HMF) into
high-value-added
products, such as 2,5-diformylfuran (DFF) and 2,5-furan dicarboxylic
acid (FDCA), through a photocatalytic process by using solar energy
has been incessantly pursued worldwide. Herein, a series of transition-metal
(TM = Ni, Fe, Co, Cu) single atoms were supported on Ti4+αTi3+1‑αO2−δ nanofibers (NFs) with certain defects (Ov),
denoted as TM SAC-Ti4+αTi3+1‑αO2−δ NFs (TM =
Ni, Fe, Co, Cu), aiming to enhance the photocatalytic conversion of
HMF. A super HMF conversion rate of 57% and a total yield of 1718.66
μmol g–1 h–1 (DFF and FDCA)
surpassing that of the Ti4+αTi3+1‑αO2−δ NFs by 1.6
and 2.1 times, respectively, are realized when TM is Co (Co SAC-Ti4+αTi3+1‑αO2−δ NFs). Experiments combined with density
functional theory calculation (DFT) demonstrate that the TM single
atoms occupy the Ti site of Ti4+αTi3+1‑αO2−δ NFs,
which plays a dominant role in the photo-oxidation of HMF. Raman,
X-ray photoelectron spectroscopy (XPS), and electron paramagnetic
resonance (EPR) characterizations confirm the strong electron local
exchange interaction in TM SAC-Ti4+αTi3+1‑αO2−δ NFs
and demonstrate the substitution of Ti by the TM SACs. The projected
density of states and charge density difference reveal that the strong
interaction between metal-3d and O-2p orbitals forms Ti–O–TM
bonds. The bonds are identified as the adsorption site, where TM single
atoms on the surface of Ti4+αTi3+1‑αO2−δ NFs reduce
HMF molecule adsorption energy (Eads).
Furthermore, the TM single atom modulates the electronic structure
of TM SAC-Ti4+αTi3+1‑αO2−δ NFs through electron transfer, leading
to narrow band gaps of the photocatalysts and enhancing their photocatalytic
performance. This study has uncovered a newer strategy for enhancing
the photocatalytic attributes of semiconducting materials
P‑Doped NiMn<sub>2</sub>O<sub>4</sub> Hollow Tubular Nanofiber Spinel Composites for Electrocatalytic Dechlorination
Electrochemical
degradation of dichloromethane (DCM) to produce
chloromethane is a hopeful strategy for the remediation of chlorinated
volatile organic compounds. However, developing high-efficiency electrocatalysts
without a noble metal remains a challenge. Here, we successfully constructed
P-doped NiMn2O4 hollow tubular nanofibers (Px-NM-HTNFs) by the combination of an electrostatic
spinning technique and a chemical vapor deposition technique, which
were used as efficient dechlorination electrocatalysts. Physicochemical
characterization and in situ characterization demonstrated that the
unique hollow tubular nanostructures and P-doped structure can effectively
accelerate charge transfer, expose more active sites, and optimize
the adsorption capacity of the electrocatalyst for DCM. The experimental
tests revealed that the P-doped electrocatalysts exhibited a remarkable
electrocatalytic dechlorination performance, achieving a chloromethane
production rate of 11665.46 μmol g–1 h–1 at −3.03 V (vs Ag/AgCl/Me4NCl)
for P1.0-NM-HTNFs. In addition, the transfer coefficient
α of 0.3 proved that the electrochemical degradation of DCM
conforms to the mechanism of synergistic dissociation electron transfer.
P1.0-NM-HTNFs generate the adsorption atom H*, thus facilitating
the dechlorination reaction. This work provides an idea for constructing
manganese–spinel composite catalysts and producing chloromethane
with high value added for DCM electrochemical dechlorination