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Abstract Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al₂O₃catalysts to modify the support to enable control over CO₂adsorption and CO₂hydrogenation activity. Significant differences in catalytic activity toward CO₂hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al₂O₃with PAs, suggesting that the reaction was mediated by CO₂adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C₃NH₂PA) and methyl phosphonic acid (C₁PA), respectively, were investigated in more detail. The C₃NH₂PA‐modified catalyst was found to bind CO₂as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO₂adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al₂O₃. CO₂adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO₂hydrogen rate trending as uncoated >C₃NH₂PA>C₁PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al₂O₃support by the PAs. 

Abstract This study investigated the high‐intensity focused ultrasound (HIFU)‐mediated propulsion of mesoporous silica nanoparticles (MSNs) and microspheres (MSMs). Nanoparticles are heavily sought as vehicles for drug delivery, but their transport through tissue is often restricted. Here, MSNs and MSMs are hydrophobically modified and coated with phospholipids to facilitate inertial cavitation to promote propulsion under HIFU. Modified nanoparticles show significantly enhanced cavitation and propulsion, achieving a maximum displacement of 250 µm (≈2500 body length) and speed of ≈1600 µm s⁻¹(16 000 body length s⁻¹), compared to unmodified nanoparticles (2 µm, 20 body length, 60 µm s⁻¹, 600 body length). In contrast, microparticles demonstrate comparable cavitation responses. Modified microparticles reached a maximum speed of 4000 µm s⁻¹(800 body length s⁻¹) and displacement of 230 µm (46 body length), and unmodified microparticles achieved 2000 µm s⁻¹(400 body length s⁻¹) and 75 µm (15 body length). In all HIFU‐responsive samples, displacement and speed decreased with successive pulses, implying that particles fatigue with continued pulsing. Analyses of particle trajectories and rotational diffusion times suggest that cavitation occurs uniformly on particle surfaces rather than at specific sites. These principles are important for the design of future drug‐delivery vehicles capable of ultrasound‐triggered motion.