P-doped g-C3N4 as the efficient photocatalyst for CO2 conversion into
value-added materials, a joint experimental and theoretical study
Abstract
The photocatalytic yield of the g-C3N4 for CO2 reduction was modified by
phosphorus doping. The possible reaction pathways for CO2 reduction on
the P-doped g-C3N4 (PCN) surface were investigated by DFT calculations
for the first time. The experimental results showed that P doping
improves the production of CH4 through the increase in the driving force
of the electrons. The partial density of states of the PCN showed that
the VBM and CBM are composed of px, py and s orbitals of the N atoms and
pz states of carbon, nitrogen, and phosphorus, respectively and
therefore, the P-doping increase carriers lifetime. Mechanism studies
confirm that formic acid, formaldehyde, methanol and methane are the
most probable products. The methane having positive adsorption energy
can be easily desorbed from the PCN surface and the Gibbs activation
energy of the final step is 1.98 eV. The formation of H2COOH is the
rate-determining step.