Regulating Surface Facets of Metallic Aerogel Electrocatalysts by Size-Dependent Localized Ostwald Ripening

It is well known that the activity and stability of electrocatalysts are largely dependent on their surface facets. In this work, we have successfully regulated surface facets of three-dimensional (3D) metallic Au^{<i>m</i>‑<i>n</i>} aerogels by salt-induced assembly of citrate-stabilized gold nanoparticles (Au NPs) of two different sizes and further size-dependent localized Ostwald ripening at controlled particle number ratios, where <i>m</i> and <i>n</i> represent the size of Au NPs. In addition, 3D Au^{<i>m</i>‑<i>n</i>}–Pd aerogels were further synthesized on the basis of Au^{<i>m</i>‑<i>n</i>} aerogels and also bear controlled surface facets because of the formation of ultrathin Pd layers on Au^{<i>m</i>‑<i>n</i>} aerogels. Taking the electrooxidation of small organic molecules (such as methanol and ethanol) by the resulting Au^{<i>m</i>‑<i>n</i>} and Au^{<i>m</i>‑<i>n</i>}–Pd aerogels as examples, it is found that surface facets of metallic aerogels with excellent performance can be regulated to realize preferential surface facets for methanol oxidation and ethanol oxidation, respectively. Moreover, they also indeed simultaneously bear high activity and excellent stability. Furthermore, their activities and stability are also highly dependent on the area ratio of active facets and inactive facets on their surfaces, respectively, and these ratios are varied via the mismatch of sizes of adjacent NPs. Thus, this work not only demonstrates the realization of the regulation of the surface facets of metallic aerogels by size-dependent localized Ostwald ripening but also will open up a new way to improve electrocatalytic performance of 3D metallic aerogels by surface regulation

Realizing a Record Photothermal Conversion Efficiency of Spiky Gold Nanoparticles in the Second Near-Infrared Window by Structure-Based Rational Design

The current technical dilemma for gold nanoparticles as photothermal (PT) transducers in cancer therapy is that strong absorption in the second near-infrared (NIR) window is accompanied by strong scattering of the NIR light, which then overrides the absorption, thus significantly weakening the light-to-heat conversion efficiency. Here we successfully prepared spiky gold nanoparticles (spiky Au NPs) with a controlled number of spikes, designed according to our simulations and experimentally verified. Their overall sizes and the numbers, lengths, and widths of the spikes were judiciously adjusted to locate their surface plasmon resonance peaks in the second NIR window and also to achieve a higher absorption-to-extinction ratio. As a result, the spiky Au NPs with optimal size and 6 spikes exhibited a record light-to-heat conversion efficiency (78.8%) under irradiation by 980 nm light. After surface PEGylation and conjugation with a lactoferrin (LF) ligand on the resulting spiky Au NPs, they <i>in vivo</i> displayed long circulation time (blood circulation half-life of ∼300 min) and high tumor accumulation due to their larger surface-to-volume ratio. Therefore, spiky Au NPs allowed complete ablation of tumors without recurrence merely after 3 min of light irradiation at 980 nm, opening up promising prospects of cancer photothermal therapy

Realizing a Record Photothermal Conversion Efficiency of Spiky Gold Nanoparticles in the Second Near-Infrared Window by Structure-Based Rational Design

The current technical dilemma for gold nanoparticles as photothermal (PT) transducers in cancer therapy is that strong absorption in the second near-infrared (NIR) window is accompanied by strong scattering of the NIR light, which then overrides the absorption, thus significantly weakening the light-to-heat conversion efficiency. Here we successfully prepared spiky gold nanoparticles (spiky Au NPs) with a controlled number of spikes, designed according to our simulations and experimentally verified. Their overall sizes and the numbers, lengths, and widths of the spikes were judiciously adjusted to locate their surface plasmon resonance peaks in the second NIR window and also to achieve a higher absorption-to-extinction ratio. As a result, the spiky Au NPs with optimal size and 6 spikes exhibited a record light-to-heat conversion efficiency (78.8%) under irradiation by 980 nm light. After surface PEGylation and conjugation with a lactoferrin (LF) ligand on the resulting spiky Au NPs, they <i>in vivo</i> displayed long circulation time (blood circulation half-life of ∼300 min) and high tumor accumulation due to their larger surface-to-volume ratio. Therefore, spiky Au NPs allowed complete ablation of tumors without recurrence merely after 3 min of light irradiation at 980 nm, opening up promising prospects of cancer photothermal therapy