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 absorptionto-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 in vivo 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.

We investigate the effect of gold (Au) seeds prepared in cetyltrimethylammonium chloride solution (CTAC-Au seeds) on the index facets of trisoctahedral gold nanocrystals (TOH Au NCs). We demonstrate that monodisperse {331}-faceted TOH Au NCs with controllable sizes (from 60 to 255 nm) can be successfully prepared in high yield by using 3.0 nm CTAC-Au seeds or as-prepared 70 nm TOH Au NCs as seeds. We find that the electrocatalytic performance on methanol oxidation and surface enhancement Raman spectroscopy (SERS) activity of {331}-faceted TOH Au NCs is size-dependent. In comparison with well-known nanoporous gold (0.088 mA cm(-2)), {331}-faceted TOH Au NCs with sizes of 110 nm exhibit fairly high catalytic activity (0.178 mA cm(-2)) on methanol oxidation (1.0 M) in alkaline media due to the presence of increasing density of atomic steps, ledges, and kinks on the NC surfaces. Their current density is reduced by less than 7% after 500 cycling tests. {331}-Faceted TOH Au NCs with sizes of 175 nm exhibit the highest SERS activity for 4-aminothiophenol (4-ATP) molecules. The enhancement factors of a1 modes of 4-ATP molecules can reach the order of 10(9) when the 4-ATP concentration is 3 × 10(-6) M. Moreover, Raman signals (ag modes) of 4,4'-dimercaptoazobenzene (DMAB) molecules on TOH Au NCs are stronger than those on spherical Au NCs of comparable size due to the enhanced laser-induced transformation of 4-ATP molecules by high-index {331}-facets during SERS measurement. Furthermore, the SERS intensities of 4-methylbenzenethiol (4-MTP) molecules on TOH Au NCs are also higher than those on spherical Au NCs of comparable size due to sharp extremities.

The amorphous CoMoS 4 is prepared using a simple precipitation method and for the first time used as a supercapacitor material. Surprisingly, it possesses very good electrochemical behavior owing to its amorphous structure and multiple oxidation states. In a three-electrode system, the ratio capacitance of CoMoS 4 sample can reach 661 F g-1 at a current density of 1 A g-1. In the actual application of CoMoS 4 , the CoMoS 4 symmetric device shows the ratio capacitance of 142 F g-1 at 2 A g-1 ; the assembled CoMoS 4 //rGO hybrid supercapacitor also owns a high ratio capacitance of 68 F g-1 at 1 A g-1 with energy and power densities of 27.2 Wh kg-1 at 400 W kg-1 and 17 Wh kg-1 at 2400 W kg-1. Further the hybrid supercapacitor has good capacitance retention (86% after 10000 cycles), low internal and Warburg resistances.

In this study, irregularly shaped, concave cuboidal Au@AuPd nanoparticles (ISCC-Au@AuPd NPs) with high-index facets were synthesized via Pd overgrowth on pre-formed ISCC-Au NPs with a concentration of Pd precursors as low as 2%. The AuPd alloy nature of the resulting shells was confirmed by X-ray photoelectron spectroscopy, cyclic voltammogram analysis, and energy dispersive X-ray spectroscopy. Among the irregularly shaped NPs obtained, the ISCC-Au97.5@Au0.5Pd2.0 NPs display the largest electrochemically active surface area (up to 92.11 m(2) g(-1)), as their closed-packed agglomeration was prevented, and the best long-term stability with respect to ethanol oxidation (0.50 M) in alkaline media (0.30 KOH) by efficiently removing intermediates. Their mass- and ECSA-normalized current densities (4.15 A mgPd(-1) and 4.51 mA cm(-2)) are about 20.7 times and 6.9 times higher than those of commercial Pd/C catalysts (0.20 A mgPd(-1) and 0.65 mA cm(-2)), respectively.

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 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 m and n represent the size of Au NPs. In addition, 3D Au-Pd aerogels were further synthesized on the basis of Au aerogels and also bear controlled surface facets because of the formation of ultrathin Pd layers on Au aerogels. Taking the electrooxidation of small organic molecules (such as methanol and ethanol) by the resulting Au and Au-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.