Ag → NiO electron cascade-driven cocatalysts enable efficient photocatalytic ammonia-to-hydrogen conversion

Suppressing photoinduced charge recombination represents a critical challenge in photocatalytic ammonia (NH 3 ) decomposition for hydrogen (H 2 ) production. Herein, we propose a dual-cocatalyst system comprising plasmonic silver (Ag) and nickel oxide (NiO), which synergistically construct an Ag → titanium dioxide (TiO 2 ) → NiO directional electron cascade on TiO 2 surfaces through work-function-induced interfacial charge transfer. The optimized 3 %Ag-1 %NiO-TiO 2 reaches a significantly photocatalytic H 2 production rate of 2366.9 μmol/h/g from NH 3 splitting, which is 20.7, 2.1 and 1.5 folds higher than that of pristine TiO 2 (114.4 μmol/h/g), 1 %NiO-TiO 2 (1146.7 μmol/h/g) and 3 %Ag-TiO 2 (1534.1 μmol/h/g), respectively. Photoelectric characterizations confirm accelerated charge separation and transfer dynamics through synergistic interplay of NiO and Ag cocatalysts on TiO 2 . Density functional theory (DFT) calculations reveal that work function gradient among TiO 2 , NiO and Ag facilitates unidirectional electron flow from Ag to NiO through the TiO 2 bridge. The optimal nickel (Ni) d-band center position and the reduced potential-determining step energy barrier for NH 3 splitting on 3 %Ag-1 %NiO-TiO 2 are further identified as key factors governing its outstanding H 2 evolution performance. This work establishes a rational dual-cocatalyst design with unidirectional electron flow to enable efficient photocatalytic H 2 production from NH 3 splitting.