Despite　the　great　research　interest　in　two-dimensional　metal　nanowire　networks　(2D　MNWNs)　due　to　their　large　specific　surface　area　and　abundance　of　unsaturated　coordination　atoms,　their　controllable　synthesis　still　remains　a　significant　challenge.　Herein,　a　microfluidics　laminar　flow-based　approach　is　developed,　enabling　the　facile　preparation　of　large-scale　2D　structures　with　diverse　alloy　compositions,　such　as　PtBi,　AuBi,　PdBi,　PtPdBi,　and　PtAuCu　alloys.　Remarkably,　these　2D　MNWNs　can　reach　sizes　up　to　submillimeter　scale　(similar　to　220　mu　m),　which　is　significantly　larger　than　the　evolution　from　the　1D　or　3D　counterparts　that　typically　measure　only　tens　of　nanometers.　The　PdBi　2D　MNWNs　affords　the　highest　specific　activity　for　formic　acid　(2669.1　mA　mg(-1))　among　current　unsupported　catalysts,　which　is　103.5　times　higher　than　Pt-black,　respectively.　Furthermore,　in　situ　Fourier　transform　infrared　(FTIR)　experiments　provide　comprehensive　evidence　that　PdBi　2D　MNWNs　catalysts　can　effectively　prevent　CO*　poisoning,　resulting　in　exceptional　activity　and　stability　for　the　oxidation　of　formic　acid.