The invention relates to a method for preparing an aromatic
aldehyde /
ketone compound based on photoelectrocatalysis. A
reaction system is included and comprises an
anode solution obtained by mixing a compound in formula I and an acid solution of
metal ions, a
cathode solution, namely, an acid solution, an
anode, namely, a photocatalyst film
electrode, a
cathode Pt and a
reference electrode, namely, mercury-mercurous
sulfate; the
reaction system carries out a reaction for 1-8 h at the bias
voltage of -0.3 V-0.9 V and at the temperature of 10-70 DEG C, then the
anode solution is extracted, an organic phase is purified to obtain the compound in formula II, an inorganic phase is utilized cyclically, and a
cathode product is
hydrogen. The formulas are shown in the specification. Alkylated aromatic is indirectly and selectively oxidized into corresponding
aldehyde /
ketone through the photoelectrocatalysis technology and meanwhile
hydrogen is generated by the cathode. Photoproduction electrons are separated from a hole through an optical excitation
semiconductor, and the hole has the strong oxidizing property. Ce3+ or Mn2+ is oxidized into Ce4+ or Mn3+ in an
aqueous solution through the photoproduction hole, the alkylated aromatic is oxidized into corresponding
aldehyde /
ketone through high-valence Ce4+ or Mn3+, and Ce4+ or Mn3+ is reduced into Ce3+ or Mn2+ to form a cycle. Meanwhile, H+ of H2O can be reduced into H2 through the photoproduction electrons.