The delafossite CuCrO2 exhibits a piezo-photo-electrocatalytic activity for the oxidation of Methyl Green (MG), under sunlight. It was synthesized by sol–gel route with an increased surface/volume ratio; the porosity is shown by the SEM analysis, the particles consist of a combination of spherical and dendritic grains, with an average size ranging from 0.2 to 1.5 μm. The direct transition (1.93 eV) is attributed to Cr3+: t2g – eg transition of CrO6 octahedra layers parallel to the (a, b) plane, giving CuCrO2 an anisotropic structure with reversible oxygen intercalation/desintercalation. The Intensity-Potential J(E) profile in Na2SO4 (3.5 g L-1) shows a small hysteresis loop, indicating good electrochemical stability with a high oxygen over-potential and the capacitance plot suggests p-type conduction and the acceptor states (Cu2+) originate from oxygen insertion into the layered lattice. The free potential is more cathodic than the flat band potential (Efb) of – 0.045 V, leading to spontaneous photocatalysis. The conduction band (– 1.75 V) reduce O2 to O2•- radical and as application 66% oxidation of MG (20 mg L− 1) was obtained by electro-catalysis through O2•- radicals under sunlight and a current of 200 mA. An enhancement up to 92% within 70 min has been reached by Sono-Photo-Electrocatalysis (SPE); in the “Ultrasound waves 60 kHz-Electric Current-Sunlight-CuCrO2”. The MG oxidation obeys a pseudo-zero-order kinetic with a half-life (t1/2) of 39 min and a reaction mechanism is proposed on the basis of the electrochemical study. These results are attributed to the piezoelectric and ferroelectric response of CuCrO2. Our findings offer valuable insights for developing highly efficient piezo- and ferroelectric Nano-structures for the solar energy conversion.
