In　this　study,　rhodium　(Rh)　nanoparticles　modified　by　N/S-codoped　carbon　nanosheets　were　prepared　as　a　high　performance　hydrogen　evolution　reaction　(HER)　interface　electrocatalyst　in　seawater.　Such　in　situ　formed　mesoporous　graphene-like　nanosheets　obtained　by　pyrolysis　of　guanine　sulfate　are　thin　and　have　a　high　surface　area　of　437.1　m(2)/g,　which　allows　homogeneous　dispersion　of　Rh　nanoparticles.　The　Rh　catalysts　show　unexpected　electronic　asymmetry　depending　on　the　intensity　of　Rh-support　interaction.　The　X-ray　photoelectron　spectra　results　indicate　that　the　introduction　of　sulfur　within　graphene-like　nanosheets　can　enhance　the　interaction　between　Rh　nanoparticles　and　carbon　supports,　which　promotes　the　electrons　to　be　deviated　from　Rh　and　transferred　to　the　interface　of　Rh　and　carbon,　leading　to　a　novel　interface　catalyst.　Benefiting　from　the　formation　of　an　electron-rich　interface,　this　as-prepared　Rh-based　interface　catalyst　exhibits　superior　HER　activity　during　the　whole　pH　range,　very　close　to　the　commercial　20%　Pt/C　even　when　the　loading　of　Rh　is　only　0.5　wt　%.　Even　in　seawater　(pH　=　8.32),　this　electrocatalyst　shows　high　activity　and　can　deliver　-15　mA/cm(2)　current　density　for　10　h　with　good　stability.　We　believe　this　work　may　provide　a　new　pathway　to　design　promising　electrocatalysts　for　seawater　splitting.