A simple fabrication route of porous palladium/palladium oxide/carbon nanostructures using one-step combustion waves for high-performance pH sensors

•A scalable fabrication of Pd/PdxOy@C nanostructures was developed using one-step combustion waves (CWs).•Formaldehyde in precursors transforms PdxOy from lower to higher oxidation state (PdO2) in CWs.•Instant chemical reaction in CWs formulates the hybrid-porous structures with carbon layers.•The synthesized Pd/PdxOy@C enabled the high-performance pH sensors.•High oxidation state and conductive carbon layer improved the specific potential and the stability.