Polydiacetylene-based gels for solvent discrimination and formation of Au/Ag nanoparticles with embedded photocatalytic performance

•Pollutant sensing, absorption and function particle formation could be obtained by PDA gels.•Eu3+/O-TPY-DA gel could sense organic solvents with high selectivity and dual signal outputs.•PDA gel could absorb Ag+/Au3+ from aqueous solution, followed by functional nanoparticle formation.•Ag/Au based PDA hybrids demonstrated enhanced photocatalytic performance toward p-nitrophenol.•This work fused the concepts from pollutant sensing and waste to health.