Unveiling Cl-induced electrocatalytic Cα-Cβ cleavage mechanism by 1D/2D/1D TiO2@ZIS-Sv@C heterojunction for efficient aromatic aldehyde generation

Constructing an efficient and low-cost electrocatalyst was highly necessary in electrocatalytic lignin depolymerization study. We prepared a unique 1D/2D/1D nanoflower electrocatalyst (Ti 20 @ZIS-Sv@C 0.5 (Ⅱ)) composed of TiO 2 , ZnIn 2 S 4 and C nanosheets by electrostatic self-assembly through solvothermal method. The TiO 2 was located as the core of catalyst and covered by the C deposited ZnIn 2 S 4 nanosheets. The electrochemical impedance (R ct , 248.5 Ω; R L , 6.511 Ω), C dl (1.75817 mF cm −2 ), Tafel efficiency (6.28 mV dec −1 ) and photocurrent intensity (5.23 μA) of Ti 20 @ZIS-Sv@C 0.5 (Ⅱ) exhibited higher electrocatalytic activity than that of original ZnIn 2 S 4 . Under optimized conditions, electrocatalytic process achieved 100 % C α -C β (β-O-4) and C Ar -O (α-O-4) cleavage efficiency and 244.37 mg g −1 benzaldehyde yield. We have further indicated C α -C β (β-O-4) and C Ar -O (α-O-4) cleavage mechanism by Cl-induced radical oxidation pathway. The electrocatalytic depolymerization of G-type lignin could obtained at least 14 molecular products (including 18.21 mg g −1 2-hydroxy-1-phenylethan-one, 11.39 mg g −1 pyrocatechol and 1.25 mg g −1 benzaldehyde). Mechanism investigation suggested the generation of chlorine radical (•Cl), followed by C-H activation and synergistic effect of Ti 20 @ZIS-Sv@C 0.5 (Ⅱ), leading to highly efficient lignin linkages cleavage. This work has developed an efficient electrocatalyst for lignin valorisation to produce aromatics via an electrocatalytic radical pathway.