Activation of lignin by selective oxidation: an emerging strategy for boosting lignin depolymerization to aromatics

•Efficient conversion of lignin to aromatics should deal with the condensation issue.•The activation of β-O-4 linkages is crucial for busting lignin depolymerization.•Oxidation of CαH-OH to Cα = O in β-O-4 can obviously improve lignin depolymerization.•Various oxidation strategies can be used to selectively oxidize lignin side chains.