Paper strips coated with polypyrrole-wrapped carbon nanotube composites for chemi-resistive gas sensing

•Cellulosic paper strips were coated with diazonium-modified carbon nanotubes.•The paper strips were further coated with polypyrrole and served as chemiresistive gas sensors.•The paper-based gas sensors were highly selective towards ammonia.•The limit of detection was found to be as low as 0.04 ppb.