In Situ Generation of Porous Ag‐Hollandite/Polypyrrole 2D Mats at the Water/Chloroform Interface for Dual Applications in Energy Storage and Electrochemical Sensing

A facile in situ method of the liquid/liquid (L/L) polymerization strategy for synthesizing silver-doped hollandite manganese oxide (Ag-HMO) on polypyrrole (PPy) support is reported for the first time. The highly innovative synthetic method involves producing α-MnO₂ attached to PPy oligomers under low-temperature conditions. Subsequently, Ag⁺ ions are in situ intercalated into the 2 × 2 tunnels in α-MnO₂ to generate Ag-HMO-incorporated PPy. Calculations based on density functional theory (DFT) yield negative formation energies, suggesting that Ag-HMO can be formed through the tunnel doping of Ag⁺ in α-MnO₂. Highly crystalline 2D composite mats of Ag-HMO/PPy (PAgMn) with interconnected Ag-HMO nanorod networks with a thickness of ≈1 nm are demonstrated by electron and atomic force microscopy images. Electrochemical detection of formaldehyde on PAgMn-modified screen-printed electrodes opens new prospects for real-time food adulterant sensors. PAgMn is also utilized as electrodes for supercapacitors with a high specific capacitance of 601 mF cm^-2. An all-solid-state asymmetric supercapacitor device assembled with PAgMn and activated carbon as negative and positive electrodes demonstrates outstanding energy storage capability with a remarkable energy density of 6.16 mWh cm^-2 at a power density of 6300 mW cm^-2.