Nanotechnology

Organic chemistry

Carbon nitride

Palladium

Hydrogen

Photocatalysis

Dissociation (chemistry)

Electron transfer

Methanation

Catalysis

Physical chemistry

Nanoparticle

Hydrogen production

Chemistry

Materials science

Hydrogen spillover

Photochemistry

Advanced Materials

Selective photoreduction of carbon dioxide (CO2 ) into carbon-neutral fuels such as methane (CH4 ) is extremely desirable but remains a challenge since sluggish multiple proton-electron coupling transfer and various C1 intermediates are involved. Herein, a synergistic function between single Pd atoms (Pd1 ) and Pd nanoparticles (PdNPs ) on graphitic carbon nitride (C3 N4 ) for photocatalytic CO2 methanation is presented. The catalyst achieves a high selectivity of 97.8% for CH4 production with a yield of 20.3 µmol gcat.-1 h-1 in pure water. Mechanistic studies revealed that Pd1 sites activated CO2 , while PdNPs sites boosted water (H2 O) dissociation for increased H* coverage. The H* produced by PdNPs migrate to the Pd1 sites to promote multiple proton-electron coupling transfer via hydrogen spillover. Moreover, the adjacent Pd1 and PdNPs effectively stabilized intermediates such as *CHO, thereby favoring the pathway for CH4 production. This work provides a new perspective into the development of selective photocatalytic CO2 conversion through the artful design of synergistic catalytic sites.

Synergy between Palladium Single Atoms and Nanoparticles via Hydrogen Spillover for Enhancing CO<sub>2</sub> Photoreduction to CH<sub>4</sub>

Synergy between Palladium Single Atoms and Nanoparticles via Hydrogen Spillover for Enhancing CO2 Photoreduction to CH4

Synergy between Palladium Single Atoms and Nanoparticles via Hydrogen Spillover for Enhancing CO₂ Photoreduction to CH₄