Oxygen vacancy-enriched V2O5·nH2O nanofibers ink for universal substrates-tolerant and multi means-integratable NH3 sensing

Universal substrates-tolerant and multi means-integratable ammonia (NH3) sensing is highly desired in future Internet of Things in environmental monitoring, food security and early diagnosis of human diseases, however, is still less than satisfactory. Here, an oxygen vacancy-governed NH3 sensing has been developed with V2O5·nH2O nanofibers (NFs) ink, via combined thermal decomposition of ammonium metavanadate and dilution. As-obtained NH3 sensing ink takes on red colloids, in which the V2O5·nH2O NFs around 14 nm in diameter are interconnected. Beneficially, the fabric fiber decorated with V2O5·nH2O NFs ink displays excellent selectivity and ppb-concentration detection limit. Remarkably, V2O5·nH2O NFs ink is integrated over “hard” and “flexible” substrates such as glass, wood, paper, leaf and fabric with excellent tolerance by multi-integratable means such as writing, dipping and sewing. Theoretically, such NH3 sensing is interpreted that the bonding between V2O5 NFs and H2O modulates oxygen vacancy and thus adsorption sites, and the incorporation between crystal water and free one contributes to stable ink. Practically, a sensing device built with V2O5·3.1H2O NFs ink has been simulated to communicate with a smartphone with reliable NH3 sensing.