Preparation of a conductive hydrogel based on carrageenan, polyvinyl alcohol, and polypyrrole as a potential room temperature electrochemical hydrogen gas sensor

• Car/AA/AAm/PVA/PPy hydrogel was formed via free radical then in situ polymerization. • Car/AA/AAm/PVA/PPy hydrogel has enhanced responsiveness and electrical conductivity. • The sensor had a sensitivity of 58.468 µ.A.M and detection limits of 3.435 μ.M. • The best response and recovery times of the sensor were 1.1 and 1.6 s, respectively. This study shows the development of a novel hydrogel material consisting of κ-carrageenan (Car), acrylic acid (AA), acrylamide (AAm), and polyvinyl alcohol (PVA), coated with polypyrrole (PPy), as a conductive platform for room-temperature hydrogen gas (H 2 ) sensing. The Car/AA/AAm/PVA hydrogel was synthesized via free radical polymerization, followed by in situ oxidative polymerization of PPy to form a conductive Car/AA/AAm/PPy hydrogel for hydrogen sensing. KOH was utilized as a hydrogen source, allowing for interaction with H 2 at ambient temperatures. The resultant hydrogel material was characterized using SEM, FTIR, XRD, UV, CV, EIS, LSV, and CA measurements. The sensor has the greatest sensitivity (N) at 58.468 µ.A.M −1 , a limit of detection (LOD) of 3.435 µ.M, and a response/recovery time (Rs/Rc) of 1.1/1.6 s. However, the remarkable sensing abilities of the Car/AA/AAm/PVA/PPy hydrogel are attributable to pyrrole’s conjugated structure and greater electron density. This structure facilitates increased migration of charge carrier mobility, which leads to conductivity and improves gas adsorption. Furthermore, the incorporation of PVA salt ions increased the ionic charge speed, enhanced ion transport within the hydrogel matrix, and reduced the swelling behaviour, which also led to improved hydrogen gas adsorption.