Electrolysis　of　seawater　will　alleviate　strain　on　fresh　water　scarcity.　Non-noble　metal　compounds　as　substitutes　for　precious　metals　for　oxygen　evolution　reaction　(OER)　have　been　intensively　studied.　However,　to　make　OER　electrocatalyst　efficient　and　stable　in　seawater　is　still　an　issue　to　be　solved.　In　view　of　this,　an　attempt　to　fabricate　nickel　foam　(NF)-enclosed　reduced　graphene　oxide　(rGO)　supported　sub-nanometer　arrays　of　NiFe　phosphide　is　reported.　The　as-obtained　NiFeP/P-doped　rGO/NF　(NiFeP/P-rGO/NF)　at　current　densities　of　100　and　400　mA　cm(-2)　shows　overpotentials　of　290　and　340　mV　respectively,　well　below　490　mV　overpotential　that　avoided　triggering　chloride　oxidation　in　seawater　(1　m　KOH+1　m　NaCl).　The　Tafel　slope　of　NiFeP/P-rGO/NF　is　as　low　as　71.9　mV　dec(-1).　Moreover,　no　considerable　loss　of　current　density　is　observed　after　450　h　at　35　mA　cm(-2).　This　strategy　is　extended　to　fabricate　CoFeP/P-rGO/NF　and　IrO2/rGO/NF　and　they　also　show　superior　activity.　The　combination　of　ultrathin　NiFeP　arrays　and　conductive　network　of　rGO　are　the　key　to　superior　activity.　Hydrophobicity　of　the　rGO　is　accountable　for　good　durability　in　seawater.