A　novel　photoelectrochemical　sensor　based　on　TiO2/NiPc/ZIF-67　composite　was　developed　for　ammonia　(NH3)　detection　in　water,　showing　exceptional　sensitivity　and　selectivity.　The　sensor　was　fabricated　by　depositing　TiO2,　NiPc,　and　ZIF-67　onto　an　ITO　electrode.　Under　optimized　conditions,　it　achieved　an　ultra-low　detection　limit　of　0.031　nM,　surpassing　previous　reports.　A　strong　linear　correlation　(R2　=　0.998)　was　observed　between　the　relative　value　of　the　photocurrent　and　the　logarithm　of　NH3　concentration　over　the　range　of　0.1　nM　to　10　mu　M.　TiO2　ensured　stable　photocurrent　generation,　while　ZIF-67,　a　metal-organic　framework　with　polyhedral　morphology,　adjustable　pore　size,　high　surface　area　(758.6　m2/g　BET),　and　microporous　structure,　selectively　enriched　NH3.　In　competitive　adsorption　experiments,　NH3　exhibited　a　slower　adsorption　rate　compared　to　gases　like　CO,　CH4,　N2,　and　O2,　minimizing　interference.　NiPc,　a　p-type　semiconductor　with　an　18　pi-electron　conjugated　structure,　coordinated　with　NH3　to　promote　NH3　oxidation　and　accelerate　the　reaction　rate.　The　synergistic　effect　of　NiPc　and　ZIF-67　enhanced　the　sensor　performance,　as　demonstrated　by　cyclic　voltammetry,　which　showed　that　the　electrode　potential　of　the　oxidation　process　shifts　negatively　when　both　materials　were　modified　on　a　glassy　carbon　electrode　upon　NH3　addition.　In　real　water　samples,　the　sensor　displayed　high　selectivity,　with　minimal　response　to　common　interfering　ions　such　as　Cu2+,　Mg2+,　and　Ca2+,　ensuring　accurate　NH3　detection　in　complex　environments.