Plasmonic Pd-Sb nanosheets for photothermal CH₄ conversion to HCHO and therapy

Photothermal catalysis effectively increases catalytic activity by using the photothermal effect of metal nanomaterials; however, the combination of strong light absorption and high catalytic performance remains a challenge. Here, we demonstrate hexagonal ~5-nanometer-thick palladium antimony (chemical formula as Pd₈Sb₃) nanosheets (NSs) that exhibit strong light absorption within full spectral and localized surface plasmon resonance (LSPR) effects in the visible region. Such LSPR features lead to strong photothermal effects, and Pd₈Sb₃ NSs aqueous dispersion enables enhanced photothermal methane (CH₄) conversion to formaldehyde (HCHO) under full-spectrum light irradiation at 1.7 watts per square centimeter, leading to selectivity of ~98.7%, productivity of ~665 millimoles per gram of catalyst, ~700 times higher than that of Pd NSs. Mechanism investigations suggest that different radicals were generated on Pd₈Sb₃ (·OH) and Pd NSs (·O₂^-), where Pd₈Sb₃ NSs displays stronger adsorption strength to CH₄ and facilitates CH₄ oxidation to HCHO. Besides, the strong light absorption ability of Pd₈Sb₃ NSs enables photothermal therapy for breast cancer.