Enhanced Visible-Light H2O2 Production over Pt/g-C3N4 Schottky Junction Photocatalyst.

Photocatalytic for hydrogen peroxide (H2O2) production is thought as a promising technology owing to its clean and green properties with the cheap and easily available raw materials of H2O and O2. Herein, Pt/g-C3N4 Schottky junction photocatalysts with ultralow Pt contents (0.025-0.1 wt %) were successfully fabricated by an impregnation-reduction method. It can efficiently reduce O2 to generate H2O2 without a sacrificial agent under visible-light irradiation. The yield of H2O2 produced over Pt0.05/g-C3N4 with the optimal 0.05 wt % Pt reached 31.82 µM, which was 2.46 times that of g-C3N4 and higher than most of those in the literature. It also showed good stability in three repeated tests. The deposition of highly dispersed metal Pt nanoparticles with low and limited content can expose enough active Pt atoms, significantly enhance the separation efficiency of photogenerated carriers, and reduce its negative effect on H2O2 decomposition, resulting in improved and outstanding efficiency of H2O2 production. The ·O2- radicals were found to be the main active species. The mechanism of photocatalytic H2O2 production was confirmed to be a two-step single electron route (O2 + e-→ ·O2- → H2O2).

METTL3 Regulates Osteoclast Biological Behaviors via iNOS/NO-Mediated Mitochondrial Dysfunction in Inflammatory Conditions.

Excessive differentiation of osteoclasts contributes to the disruption of bone homeostasis in inflammatory bone diseases. Methyltransferase-like 3 (METTL3), the core methyltransferase that installs an N6-methyladenosine (m6A) modification on RNA, has been reported to participate in bone pathophysiology. However, whether METTL3-mediated m6A affects osteoclast differentiation in inflammatory conditions remains unelucidated. In this study, we observed that the total m6A content and METTL3 expression decreased during LPS-induced osteoclastogenesis. After knocking down METTL3, we found reduced levels of the number of osteoclasts, osteoclast-related gene expression and bone resorption area. A METTL3 deficiency increased osteoclast apoptosis and pro-apoptotic protein expression. RNA sequencing analysis showed that differentially expressed genes in METTL3-deficient cells were mainly associated with the mitochondrial function. The expression of the mitochondrial function-related genes, ATP production and mitochondrial membrane potential decreased after METTL3 knockdown. Moreover, the most obviously upregulated gene in RNA-Seq was Nos2, which encoded the iNOS protein to induce nitric oxide (NO) synthesis. METTL3 knockdown increased the levels of Nos2 mRNA, iNOS protein and NO content. NOS inhibitor L-NAME rescued the inhibited mitochondrial function and osteoclast formation while suppressing osteoclast apoptosis in METTL3-silenced cells. Mechanistically, a METTL3 deficiency promoted the stability and expression of Nos2 mRNA, and similar results were observed after m6A-binding protein YTHDF1 knockdown. Further in vivo evidence revealed that METTL3 knockdown attenuated the inflammatory osteolysis of the murine calvaria and suppressed osteoclast formation. In conclusion, these data suggested that METTL3 knockdown exacerbated iNOS/NO-mediated mitochondrial dysfunction by promoting a Nos2 mRNA stability in a YTHDF1-dependent manner and further inhibited osteoclast differentiation and increased osteoclast apoptosis in inflammatory conditions.

YTHDF1 regulates endoplasmic reticulum stress, NF-κB, MAPK and PI3K-AKT signaling pathways in inflammatory osteoclastogenesis.

Abnormal increases in osteoclast differentiation and activity contribute to excessive bone resorption in inflammatory bone diseases. The specific m6A-binding protein YT521-B homology domain family 1 (YTHDF1) participates in many physiopathological processes by regulating mRNA stability or translation. However, whether YTHDF1 is involved in the regulation of inflammatory osteoclastogenesis remains a mystery. This study revealed that YTHDF1 expression was upregulated during lipopolysaccharide (LPS)-stimulated osteoclast differentiation. Knockdown of Ythdf1 inhibited osteoclast formation, bone resorption and the expression of osteoclast-related genes (Tnfrsf11a, Traf6, Mmp9 and Acp5). Analysis of RNA sequencing data showed that the genes downregulated by Ythdf1 knockdown were closely associated with endoplasmic reticulum (ER) stress and osteoclast differentiation. Western blotting confirmed that Ythdf1 depletion suppressed activation of the ER stress-related PERK, IRE1α and ATF6 signaling pathways. The ER stress activator tunicamycin (Tm) partially rescued the decreased expression of Mmp9 and Acp5 caused by Ythdf1 deficiency. Meanwhile, Ythdf1 depletion inhibited the phosphorylation levels of key proteins in the NF-κB, MAPK and PI3K-AKT signaling pathways and decreased the mRNA stability of Tnfrsf11a, which is the major upstream signaling molecule that mediates the activation of these pathways during osteoclast differentiation. In conclusion, our findings suggest that Ythdf1 knockdown inhibits inflammatory osteoclast differentiation and function by suppressing ER stress signaling pathways. Ythdf1 knockdown also inactivates the signaling pathways involved in osteoclast differentiation by inhibiting Tnfrsf11a mRNA stability. These findings will help shed light on the molecular mechanisms of m6A-mediated epigenetic regulation in inflammatory osteoclastogenesis.

Ultrathin and Porous 2D PtPdCu Nanoalloys as High-Performance Multifunctional Electrocatalysts for Various Alcohol Oxidation Reactions.

We precisely synthesized two-dimensional (2D) PtPdCu nanostructures with the morphology varying from porous circular nanodisks (CNDs) and triangular nanoplates (TNPs) to triangular nanoboomerangs (TNBs) by tuning the molar ratios of metal precursors. The PtPdCu trimetallic nanoalloys exhibit superior electrocatalytic performances to alcohol oxidation reactions due to their unique structural features and the synergistic effect. Impressively, PtPdCu TNBs exhibit a high mass activity of 3.42 mgPt+Pd-1 and 1.06 A·mgPt-1 for ethanol and methanol oxidation compared to PtPd, PtCu, and pure Pt, which is 3.93 and 4.07 times that of commercial Pt/C catalysts, respectively. Moreover, 2D PtPdCu TNPs and PtPdCu CNDs also show a highly improved electrocatalytic activity. Furthermore, as all-in-one electrocatalysts, PtPdCu nanoalloys display excellent electrocatalytic activity and stability toward the oxidation of other alcohol molecules, such as isopropyl alcohol, glycerol, and ethylene glycol. The enhanced mechanism was well proposed to be the abundant active sites and upshifted d-band center based on density functional theory calculations.

YTHDF2 mediates LPS-induced osteoclastogenesis and inflammatory response via the NF-κB and MAPK signaling pathways.

Aberrant elevation of osteoclast differentiation and function is responsible for disrupting bone homeostasis in various inflammatory bone diseases. YTH domain family 2 (YTHDF2) is a well-known m6A-binding protein that plays an essential role in regulating cell differentiation and inflammatory processes by mediating mRNA degradation. However, the regulatory role of YTHDF2 in inflammatory osteoclast differentiation remains unelucidated. Here, we detected the expression of m6A-related genes and found that YTHDF2 was upregulated in RANKL-primed osteoclast precursors stimulated with lipopolysaccharide (LPS). Ythdf2 knockdown in RAW264.7 cells and primary bone marrow-derived macrophages (BMMs) enhanced osteoclast formation and bone resorption, which was assessed by TRAP staining assay and pit formation assay. Ythdf2 depletion upregulated osteoclast-related gene expression and proinflammatory cytokine secretion. In contrast, overexpression of Ythdf2 produced the reverse effect. Furthermore, Ythdf2 knockdown enhanced the phosphorylation of IKKα/ß, IκBα, ERK, P38 and JNK. NF-κB and MAPK signaling pathway inhibitors effectively abrogated the enhanced expression of Nfact1, c-Fos, IL-1ß and TNF-α caused by Ythdf2 knockdown. Mechanistically, the mRNA stability assay revealed that Ythdf2 depletion led to stabilization of Tnfrsf11a, Traf6, Map4k4, Map2k3, Map2k4 and Nfatc1 mRNA. In summary, our findings demonstrated that YTHDF2 has a negative regulatory role in LPS-induced osteoclast differentiation and the inflammatory response via the NF-κB and MAPK signaling pathways.

Platinum-Based Electrocatalysts for Direct Alcohol Fuel Cells: Enhanced Performances toward Alcohol Oxidation Reactions.

In the past few decades, Pt-based electrocatalysts have attracted great interests due to their high catalytic performances toward the direct alcohol fuel cell (DAFC). However, the high cost, poor stability, and the scarcity of Pt have markedly hindered their large-scale utilization in commerce. Therefore, enhancing the activity and durability of Pt-based electrocatalysts, reducing the Pt amount and thus the cost of DAFC have become the keys for their practical applications. In this minireview, we summarized some basic concepts to evaluate the catalytic performances in electrocatalytic alcohol oxidation reaction (AOR) including electrochemical active surface area, activity and stability, the effective approaches for boosting the catalytic AOR performance involving size decrease, structure and morphology modulation, composition effect, catalyst supports, and assistance under other external energies. Furthermore, we also presented the remaining challenges of the Pt-based electrocatalysts to achieve the fabrication of a real DAFC.

Ru Nanoworms Loaded TiO2 for Their Catalytic Performances toward CO Oxidation.

Ruthenium nanocrystals with small size and special morphology are of great interest in various catalytic reactions due to their high activities. However, it is still a great challenge to downsize these nanocatalysts to a sub-nano scale (<2 nm). Herein, we reported a synthesis of ultrasmall size and uniform Ru nanoparticles through a rapid one-pot method. The prepared Ru nanocrystal shows a wormlike shape, in which the diameter is as thin as 1.6 ± 0.3 nm and the length is 13.6 ± 4.4 nm. These Ru nanoworms (NWs) are quite steady during the synthetic process even though the reaction time was further prolonged. We also examined their catalytic activity toward CO oxidation by loading Ru NWs on TiO2 to form Ru NWs/TiO2 catalysts. These catalysts exhibit a high activity of 100% CO conversion at 150 °C, which is much lower than the normal Ru NPs/TiO2 nanostructures. Based on our detailed investigations, we proposed that the small size, special morphology, and TiO2 support are the keys for their significantly improved catalytic activity. We believed that these reasonable discoveries provide a methodology and opportunity to get highly active catalysts for CO oxidation by a detailed increase in their active sites.

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible-Light Illumination.

Plasmonic nanostructures with large absorption areas under resonant excitation have been utilized extensively in photon-assisted applications. In this work, dodecahedral Au nanobowls were first prepared by an easy and template-free method only through the introduction of H2 PtCl6 and I- during the growth procedure. The Au nanobowls show electron-field enhancement due to the high curvature of the bowl edge, the open region, and dodecahedral morphology. Au/Pt nanobowls, which couple plasmonic Au and catalytic Pt, were then constructed as plasmonic electrocatalysts for methanol oxidation. The mass activity reached 497.6 mA mg-1 under visible-light illumination, which is 1.9 times that measured in the dark. Simultaneously, the electrocatalytic stability is also greatly improved under light excitation. The enhanced properties of the plasmonic Au/Pt electrocatalysts are ascribed to the synergistic effect of the plasmon-enhanced photothermal and hot-carrier effects on the basis of experimental investigations. This work thus offers an effective methodology to construct efficient plasmonic electrocatalysts for fuel cells.

Titania supported synergistic palladium single atoms and nanoparticles for room temperature ketone and aldehydes hydrogenation.

Selective reduction of ketone/aldehydes to alcohols is of great importance in green chemistry and chemical engineering. Highly efficient catalysts are still demanded to work under mild conditions, especially at room temperature. Here we present a synergistic function of single-atom palladium (Pd1) and nanoparticles (PdNPs) on TiO2 for highly efficient ketone/aldehydes hydrogenation to alcohols at room temperature. Compared to simple but inferior Pd1/TiO2 and PdNPs/TiO2 catalysts, more than twice activity enhancement is achieved with the Pd1+NPs/TiO2 catalyst that integrates both Pd1 and Pd NPs on mesoporous TiO2 supports, obtained by a simple but large-scaled spray pyrolysis route. The synergistic function of Pd1 and PdNPs is assigned so that the partial Pd1 dispersion contributes enough sites for the activation of C=O group while PdNPs site boosts the dissociation of H2 molecules to H atoms. This work not only contributes a superior catalyst for ketone/aldehydes hydrogenation, but also deepens the knowledge on their hydrogenation mechanism and guides people to engineer the catalytic behaviors as needed.

High-Density Pd Nanorod Arrays on Au Nanocrystals for High-Performance Ethanol Electrooxidation.

In the synthesis of Au/Pd bimetallic nanocrystals, a layer-by-layer growth is favored, owing to the low bonding energy between Pd atoms ( EPd-Pd) in comparison with EAu-Pd, resulting in homogeneous core/shell nanostructures. Herein, we demonstrate designed synthetic tactics to unconventional Au/Pd heterostructures through a deposition-dominant growth pathway of the newly reduced Pd atoms, which break the intrinsically favored layer-by-layer growth. Pd thus grows on Au seeds in a heterogeneous nucleation manner. The resulting anisotropic Pd nanorods array on the two basal facets and three side facets of the Au triangular seeds in a high density to form 2D/1D Au/Pd heterostructures. It is noticed that Pd nanorods align in an extremely high order. They grow almost in a row with the base of the rod located overlapped on the Au surface. This versatile approach has been also applied to other Au nanocrystal seeds, involving hexagonal nanoplates, circular nanodisks, nanorods, and nanobipyramids. Furthermore, the 2D/1D Au/Pd heterostructures exhibit an enhanced electrocatalytic performance toward ethanol oxidation in alkaline condition, owing to their unique structure and the exposure of Au. We believe that our synthetic strategy is highly valuable for the construction of multimetallic nanostructures with desired architectures and thus intriguing properties.

AuPt Bipyramid Nanoframes as Multifunctional Platforms for In†Situ Monitoring of the Reduction of Nitrobenzene and Enhanced Electrocatalytic Methanol Oxidation.

Multifunctional metal nanostructures with a hollow feature, especially for nanoframes, are highly attractive owing to their high surface-to-volume ratios. However, pre-grown metal nanocrystals are always involved during the preparation procedure, and a synthetic strategy without the use of a pre-grown template is still a challenge. In this article, a template-free strategy is reported for the preparation of novel AuPt alloy nanoframes through simply mixing HAuCl4 and H2 PtCl6 under mild conditions. The alloy nanostructures show a bipyramid-frame hollow architecture with the existence of only the ten ridges and absence of their side faces. This is the first report of bipyramid-like nanoframes and a template-free method under mild conditions. This configuration merges the plasmonic features of Au and highly active catalytic sites of Pt in a single nanostructure, making it an ideal multifunctional platform for catalyzing and monitoring the catalytic reaction in real time. The superior catalytic activity is demonstrated by using the reduction of nitrobenzene to the corresponding aminobenzene as a model reaction. More importantly, the AuPt nanoframes can track the reduction process on the basis of the SERS signals of the reactants, intermediates, and products, which helps to reveal the reaction mechanism. In addition, the AuPt nanoframes show much higher electrocatalytic properties toward the methanol oxidation reaction than commercial Pt/C electrocatalysts.

Engineering of Hollow PdPt Nanocrystals via Reduction Kinetic Control for Their Superior Electrocatalytic Performances.

Synthesis of hollow metal nanocrystals (NCs) is greatly attractive for their high active surface areas, which gives rise to excellent catalytic activity. Taking PdPt alloy nanostructure as an example, we designed a synthetic tactic for the preparation of hollow metal nanostructures by delicate control over the difference in the reduction kinetic of metal precursors. At a high reduction rate difference, the Pd layer forms from H2PdCl4 and is subsequently etched, leading to the formation of a hollow space. A solid PdPt structure is achieved when the reduction rate of Pd and Pt precursor is comparable. Obviously, the hollow space and composition are tunable as well by adjusting the reduction rate difference. More importantly, the prepared hollow PdPt nanostructures exhibit a branched outer, porous wall, and rough hollow interior. The branched outer and rough hollow interior provide the higher density of unsaturated atoms, whereas the porous wall serves as channels connecting the inner, outer, and reactive agents. Moreover, the periodic self-consistent density function theory suggests that the d-band theory density of state of the PdPt nanoalloys is upshifted in comparison to the monometallic component, which will beneficial for improvement in their catalytic performances. Electrocatalytic tests reveal that the PdPt bimetallic NCs, especially for Pt32Pd68 nanostructures, show excellent catalytic activity and stability toward methanol oxidation reaction owing to their special structures as well as compositions.

Facile Growth of High-Yield Gold Nanobipyramids Induced by Chloroplatinic Acid for High Refractive Index Sensing Properties.

Au nanobipyramids (NBPs) have attracted great attention because of their unique localized surface plasmon resonance properties. However, the current growth methods always have low yield or suffer tedious process. Developing new ways to direct synthesis of high-yield Au NBPs using common agents is therefore desirable. Here, we employed chloroplatinic acid as the key shape-directing agent for the first time to grow Au NBPs using a modified seed-mediated method at room temperature. H2PtCl6 was added both during the seed preparation and in growth solution. Metallic Pt, reduced from chloroplatinic acid, will deposit on the surface of the seed nanoparticles and the Au nanocrystals and thus plays a critical role for the formation of Au NBPs. Additionally, the reductant, precursor, and surfactant are all cheap and commonly used. Furthermore, the Au NBPs offer narrow size distribution, two sharp tips, and a shared basis. Au NBPs therefore show much higher refractive index sensitivities than that of the Au nanorods. The refractive index sensitivities and lager figure of merit values of Au NBPs exhibit an increase of 63% and 321% respectively compared to the corresponding values of Au nanorod sample.

Simultaneous tunable structure and composition of PtAg alloyed nanocrystals as superior catalysts.

PtAg alloyed nanostructural catalysts were firstly prepared by co-reduction of AgNO3 and H2PtCl6 precursors in growth solution using a seed-mediated method. By simply changing the molar ratio of the metal precursors, the morphologies of the porous alloyed nanocrystals can be tuned from multipetals to multioctahedra. Simultaneously, the alloy composition can be varied from Pt76Ag24 to Pt66Ag34. The catalytic properties of the prepared PtAg alloyed nanocrystals with a tunable structure and composition were tentatively examined by choosing the reduction of 4-nitrophenol with NaBH4. The reaction rate normalized to the concentration of catalysts was calculated to be 318.9 s(-1) mol(-1) L and 277.4 s(-1) mol(-1) L for Pt70Ag30 and Pt66Ag34 porous catalysts, which is much higher than the pure Pt catalysts. Moreover, PtAg nanostructures can also serve as efficient electrocatalysts toward the methanol oxidation reaction, especially for Pt70Ag30 and Pt66Ag34 porous nanocrystals. The electrocatalytic activity and the durability were both highly enhanced compared to the commercial Pt/C catalyst. In addition, we also investigated the enhancement mechanism.

Highly enhanced transverse plasmon resonance and tunable double Fano resonances in gold@titania nanorods.

Gold nanorods have attracted intensive interest owing to their localized surface plasmon resonance properties and enormous potential applications. The transverse plasmon of Au nanorods is usually weaker than the longitudinal one, hampering certain plasmonic applications. Herein we report on the intensification of the transverse plasmon resonance by coating TiO2 onto Au nanorods. The transverse plasmon mode of the resultant Au@TiO2 nanorods with a sufficiently thick shell can be comparable to or even stronger than the longitudinal one in intensity. Moreover, both the transverse and longitudinal plasmon resonances of the Au@TiO2 nanorods exhibit an asymmetric line shape on their scattering spectra. Electrodynamic simulations and analyses based on a coupled oscillator model suggest that the asymmetric line shape originates from the coupling between the Au core and TiO2 shell. Apart from the shell thickness, the plasmonic properties of the Au@TiO2 nanorods can also be tuned by the dimension of the Au nanorod core. In addition, the polarization-dependent light scattering from the individual Au@TiO2 nanorods has also been investigated. These results will be of high importance for understanding the interactions between noble metals and semiconductors in plasmonic hybrid nanosystems, and for designing novel plasmonic nanostructures with desired optical properties and functions.

Synthesis of Absorption-Dominant Small Gold Nanorods and Their Plasmonic Properties.

Absorption-dominant small Au nanorods with diameters of less than 10 nm are prepared using a facile seed-mediated growth method. The diameters of the small gold nanorods range from 6 to 9 nm, and their lengths vary from 16 to 45 nm. Their aspect ratios can be tailored from 2.7 to 4.7. As a result, the longitudinal plasmon resonance wavelengths are readily tunable from ∼720 nm to ∼830 nm by changing the seed-to-Au(III) molar ratio in the growth solution. The fractions of the scattering in the total extinction of the small Au nanorods are found to be in the range of 0.005 to 0.025 with finite-difference time-domain simulations, confirming that the extinction values of these small Au nanorods are dominantly contributed to by the light absorption. Moreover, the small Au nanorod sample is coated with a dense silica layer for photothermal therapy with three cell lines. It shows improved photothermal therapy performance compared to a large Au nanorod sample for the same cellular Au contents. Our study suggests that small Au nanorods are promising light absorbers and photothermal therapy agents.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates.

Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances.

Cellular uptake behaviour, photothermal therapy performance, and cytotoxicity of gold nanorods with various coatings.

With the development of Au nanorods for a number of biomedical applications, understanding their cellular responses has become increasingly important. In this study, we systematically evaluated the cellular uptake behaviour and cytotoxicity of Au nanorods with various surface coatings, including organic cetyltrimethylammonium bromide (CTAB), poly(sodium 4-styrenesulfonate) (PSS), and poly(ethylene glycol) (PEG), and inorganic mesoporous silica (mSiO2), dense silica (dSiO2), and titanium dioxide (TiO2). The cellular behaviour of Au nanorods was found to be highly dependent on both the surface coating and the cell type. CTAB-, PSS-, and mSiO2-coated Au nanorods exhibit notable cytotoxicity, while PEG-, dSiO2-, and TiO2-coated Au nanorods do not induce cell injury. Optical imaging studies indicated that the cell type plays a preferential role in Au nanorod cellular uptake. Higher cellular uptake of Au nanorods was seen in U-87 MG, PC-3, MDA-MB-231, and RAW 264.7 cells, as opposed to HepG2 and HT-29 cells. In addition, Au nanorod cellular uptake is also highly affected by serum protein binding to the surface coating. mSiO2-, dSiO2-, and TiO2-coated Au nanorods show significantly higher cellular uptake than PSS- and PEG-coated ones, which results in a better photothermal ablation effect for Au nanorods with the inorganic surface coatings. Our study provides valuable insights into the effects of the surface modification on the biocompatibility, cellular uptake, as well as biomedical functions of Au nanorods.

Metal/Semiconductor hybrid nanostructures for plasmon-enhanced applications.

Hybrid nanostructures composed of semiconductor and plasmonic metal components are receiving extensive attention. They display extraordinary optical characteristics that are derived from the simultaneous existence and close conjunction of localized surface plasmon resonance and semiconduction, as well as the synergistic interactions between the two components. They have been widely studied for photocatalysis, plasmon-enhanced spectroscopy, biotechnology, and solar cells. In this review, the developments in the field of (plasmonic metal)/semiconductor hybrid nanostructures are comprehensively described. The preparation of the hybrid nanostructures is first presented according to the semiconductor type, as well as the nanostructure morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then elucidated. Lastly, possible future research in this burgeoning field is discussed.

Correlating the plasmonic and structural evolutions during the sulfidation of silver nanocubes.

Ag/Ag2S hybrid nanostructures have recently received much attention, because of their synthetically tunable plasmonic properties and enhanced chemical stability. Sulfidation of pregrown Ag nanocrystals is a facile process for making Ag/Ag2S nanostructures. Understanding the sulfidation process can help in finely controlling the compositional and structural parameters and in turn tailoring the plasmonic properties. Herein we report on our study of the structural and plasmonic evolutions during the sulfidation process of Ag nanocubes, which is carried out at both the ensemble and single-particle levels. Ensemble extinction measurements show that sulfidation first causes the disappearance of the high-order triakontadipolar plasmon modes, which have electric charges located on the sharp vertices and edges of Ag nanocubes, suggesting that sulfidation starts at the vertices of Ag nanocubes. As sulfidation goes on, the dipolar plasmon peak gradually red-shifts, with its intensity first decreasing and then increasing. Electron microscopy characterizations reveal that sulfidation progresses from the outer region to the center of Ag nanocubes. The cubic shape is maintained throughout the sulfidation process, with the edge length being increased gradually. Single-particle scattering measurements show that the dipolar plasmon peak red-shifts and decreases in intensity during sulfidation. An additional scattering peak appears at a shorter wavelength at the late stage of sulfidation. The difference in the sulfidation behavior between ensemble and single-particle measurements is understood with electrodynamic simulations. During ensemble measurements, the Ag core is increasingly truncated, and it becomes a nanosphere eventually. Sulfidation stops at an intermediate stage. During single-particle measurements, Ag nanocubes are completely transformed into Ag2S, leading to the observation of the shorter-wavelength scattering peak.