The　ability　to　substitute　oxygen　evolution　reaction　(OER)　in　water　splitting　with　ammonia　oxidation　reaction　(AOR)　represents　an　important　endeavor　in　producing　high-purity　hydrogen　with　the　lowered　energy　consumption.　Due　to　the　reduced　overpotential　of　AOR　over　OER　and　preventing　the　hydrogen　and　oxygen　mixing　and　thus　possible　explosion.　Herein,　we　report　the　substitution　of　slow-kinetics　OER　with　AOR　to　effectively　boost　hydrogen　evolution　reaction　(HER)　of　wastewater　electrolysis,　thereby　rendering　energy　saving　as　well　as　decontamination　of　ammonia　(NH3)　in　wastewater.　Three-dimensional　CoS@NiCu　electrodeposited　on　Ni　foam　is　employed　as　self-supporting　bifunctional　electrocatalysts　for　both　AOR　and　HER.　The　XPS　and　in-situ　Raman　studies　reveal　the　generation　of　electrocatalytically　active　cobalt　oxyhydroxide　(CoOOH)　on　CoS@NiCu　during　the　course　of　AOR.　Interestingly,　the　density　functional　theory　(DFT)　calculation　unveils　that　NH3　preferentially　adsorbing　on　the　surface　of　electrocatalyst　prolongs　the　Co-S　bond　length,　thus　promoting　the　bond　cleavage　and　accelerating　the　formation　of　active　CoOOH　species.　Moreover,　the　rate-determining　step　of　AOR　according　to　the　Gerischer-Mauerer　(G-M)　mechanism　only　has　a　1.79　eV　energy　barrier　to　overcome.　The　electrochemical　impedance　spectroscopy　investigation　suggests　that　the　AOR　enables　an　enhanced　interfacial　charge　transfer.　As　such,　the　hydrogen　evolution　rate　of　the　AOR-HER　system　reaches　41.9　μmol　h−1,　representing　3.2-fold　increase　in　hydrogen　production　over　the　conventional　OER-HER　water　splitting.　This　study　highlights　a　promising　perspective　of　integrating　AOR　with　HER　to　synergize　efficient　hydrogen　production.　©　2023　Elsevier　Ltd