Noble metal single atoms coordinated with highly electronegative atoms, especially N and O, often suffer from an electron-deficient state or poor stability, greatly limiting their wide application in the field of catalysis. Herein we demonstrate a new PH3 -promoted strategy for the effective transformation of noble metal nanoparticles (MNPs, M=Ru, Rh, Pd) at a low temperature (400 °C) into a class of thermally stabilized phosphorus-coordinated metal single atoms (MPSAs) on g-C3 N4 nanosheets via the strong Lewis acid-base interaction between PH3 and the noble metal. Experimental work along with theoretical simulations confirm that the obtained Pd single atoms supported on g-C3 N4 nanosheets exist in the form of PdP2 with a novel electron-rich feature, conceptionally different from the well-known single atoms with an electron-deficient state. As a result of this new electronic property, PdP2 -loaded g-C3 N4 nanosheets exhibit 4 times higher photocatalytic H2 production activity than the state-of-art N-coordinated PdSAs supported on g-C3 N4 nanosheets. This enhanced photocatalytic activity of phosphorus-coordinated metal single atoms with an electron-rich state was quite general, and also observed for other active noble metal single atom catalysts, such as Ru and Rh.
Keywords: hydrogen evolution reaction; noble metals; thermolysis.
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