The CNx|Ni2P photocatalyst was prepared according to previous literature protocols with minor modifications. Briefly, unfunctionalized carbon-nitride (CNx) was first prepared by heating 2 g of melamine to 550 ºC under air for 4 h (ramping rate 5 ºC min -1 ) in a covered crucible. 300 mg of the as-prepared CNx was then mixed with NiCl2•6H2O (20 mg for 2 wt.%) in minimum volume of MilliQ ® water (1 mL), followed by stirring and sonication for 1 h each. NaH2PO2•H2O was then added to the reaction mixture and again stirred for 1 h, followed by bath sonication for another 1 h. The mixture was dried in-vacuo at 60 ºC and the dry solid obtained was heated at 200 ºC for 1 h under Ar atmosphere (ramping rate 5º min -1 ). The CNx|Ni2P powder obtained after cooling to room temperature was washed with ethanol and water and dried in-vacuo at 60 ºC.