Quantitative analysis is a great challenge in surface-enhanced Raman scattering (SERS). Core-molecule-shell nanoparticles with two components in the molecular layer, a framework molecule to form the shell, and a probe molecule as a Raman internal standard, were rationally designed for quantitative SERS analysis. The signal of the embedded Raman probe provides effective feedback to correct the fluctuation of samples and measuring conditions. Meanwhile, target molecules with different affinities can be adsorbed onto the shell. The quantitative analysis of target molecules over a large concentration range has been demonstrated with a linear response of the relative SERS intensity versus the surface coverage, which has not been achieved by conventional SERS methods.

Similar to heterostructures composed of different materials, possessing unique properties due to the synergistic effect between different components, the crystal-phase heterostructures, one variety of hetero-phase structures, composed of different crystal phases in monometallic nanomaterials are herein developed, in order to explore crystal-phase-based applications. As novel hetero-phase structures, amorphous/crystalline heterostructures are highly desired, since they often exhibit unique properties, and hold promise in various applications, but these structures have rarely been studied in noble metals. Herein, via a one-pot wet-chemical method, a series of amorphous/crystalline hetero-phase Pd nanosheets is synthesized with different crystallinities for the catalytic 4-nitrostyrene hydrogenation. The chemoselectivity and activity can be fine-tuned by controlling the crystallinity of the as-synthesized Pd nanosheets. This work might pave the way to preparing various hetero-phase nanostructures for promising applications.

Various kinds of amorphous materials, such as transition metal dichalcogenides, metal oxides, and metal phosphates, have demonstrated superior electrocatalytic performance compared with their crystalline counterparts. Compared to other materials for electrocatalysis, noble metals exhibit intrinsically high activity and excellent durability. However, it is still very challenging to prepare amorphous noble‐metal nanomaterials due to the strong interatomic metallic bonding. Herein, the discovery of a unique thiol molecule is reported, namely bismuthiol I, which can induce the transformation of Pd nanomaterials from face‐centered‐cubic (fcc) phase into amorphous phase without destroying their integrity. This ligand‐induced amorphization is realized by post‐synthetic ligand exchange under ambient conditions, and is applicable to fcc Pd nanomaterials with different capping ligands. Importantly, the obtained amorphous Pd nanoparticles exhibit remarkably enhanced activity and excellent stability toward electrocatalytic hydrogen evolution in acidic solution. This work provides a facile and effective method for preparing amorphous Pd nanomaterials, and demonstrates their promising electrocatalytic application.

Heterostructured, including heterophase, noble-metal nanomaterials have attracted much interest due to their promising applications in diverse fields. However, great challenges still remain in the rational synthesis of well-defined noble-metal heterophase nanostructures. Herein, we report the preparation of Pd nanoparticles with an unconventional hexagonal close-packed (2H type) phase, referred to as 2H-Pd nanoparticles, via a controlled phase transformation of amorphous Pd nanoparticles. Impressively, by using the 2H-Pd nanoparticles as seeds, Au nanomaterials with different crystal phases epitaxially grow on the specific exposed facets of the 2H-Pd, i.e., facecentered cubic (fcc) Au (fcc-Au) on the (002) h facets of 2H-Pd while 2H-Au on the other exposed facets, to achieve well-defined fcc-2H-fcc heterophase Pd@Au core−shell nanorods. Moreover, through such unique facet-directed crystal-phase-selective epitaxial growth, a series of unconventional fcc-2H-fcc heterophase core−shell nanostructures, including Pd@Ag, Pd@Pt, Pd@PtNi, and Pd@PtCo, have also been prepared. Impressively, the fcc-2H-fcc heterophase Pd@Au nanorods show excellent performance toward the electrochemical carbon dioxide reduction reaction (CO 2 RR) for production of carbon monoxide with Faradaic efficiencies of over 90% in an exceptionally wide applied potential window from −0.9 to −0.4 V (versus the reversible hydrogen electrode), which is among the best reported CO 2 RR catalysts in H-type electrochemical cells.

Quantitative analysis is agreat challenge in surfaceenhanced Raman scattering (SERS). Core-molecule-shell nanoparticles with two components in the molecular layer, aframework molecule to form the shell, and aprobe molecule as aR aman internal standard, were rationally designed for quantitative SERS analysis.T he signal of the embedded Raman probe provides effective feedback to correct the fluctuation of samples and measuring conditions.M eanwhile, target molecules with different affinities can be adsorbed onto the shell. The quantitative analysis of target molecules over al arge concentration range has been demonstrated with al inear response of the relative SERS intensity versus the surface coverage,which has not been achieved by conventional SERS methods.

The class III phosphoinositide 3-kinase VPS34 plays a key role in the regulation of vesicular trafficking and macroautophagy. So far, we know little about the molecular mechanism of VPS34 activation besides its interaction with regulatory proteins to form complexes. Here, we report that VPS34 is specifically acetylated by the acetyltransferase p300, and p300-mediated acetylation represses VPS34 activity. Acetylation at K771 directly diminishes the affinity of VPS34 for its substrate PI, while acetylation at K29 hinders the VPS34-Beclin 1 core complex formation. Inactivation of p300 induces VPS34 deacetylation, PI3P production, and autophagy, even in AMPK, TSC2, or ULK1 cells. In fasting mice, liver autophagy correlates well with p300 inactivation/VPS34 deacetylation, which facilitates the clearance of lipid droplets in hepatocytes. Thus, p300-dependent VPS34 acetylation/deacetylation is the physiological key to VPS34 activation, which controls the initiation of canonical autophagy and of non-canonical autophagy in which the upstream kinases of VPS34 can be bypassed.

Heterostructures consisting of distinct components have attracted considerable attention due to their unique properties and promising applications in catalysis enabled by the synergistic effect among different components. [1][2][3][4][5] Since phase engineering of nanomaterials (PEN) provides various strategies to rationally design and synthesize nanomaterials with novel crystal phases, [6] the delicate modu lation of crystal phases of each component in heterostructures with diverse morpho logies becomes possible, which is of great importance to realize tunable physical and chemical properties and enhanced perfor mances. In addition to controlling their compositions, morphologies, architec tures, facets, sizes, and dimensionalities, tremendous efforts have been devoted to constructing heterostructures con sisting of different phases during recent years. For example, highly luminescent CdSe/CdS heterostructure with tetrapod Phase engineering of nanomaterials (PEN) offers a promising route to rationally tune the physicochemical properties of nanomaterials and further enhance their performance in various applications. However, it remains a great challenge to construct well-defined crystalline@amorphous core-shell heterostructured nanomaterials with the same chemical components. Herein, the synthesis of binary (Pd-P) crystalline@amorphous heterostructured nanoplates using Cu 3−χ P nanoplates as templates, via cation exchange, is reported. The obtained nanoplate possesses a crystalline core and an amorphous shell with the same elemental components, referred to as c-Pd-P@a-Pd-P. Moreover, the obtained c-Pd-P@a-Pd-P nanoplates can serve as templates to be further alloyed with Ni, forming ternary (Pd-Ni-P) crystalline@amorphous heterostructured nanoplates, referred to as c-Pd-Ni-P@a-Pd-Ni-P. The atomic content of Ni in the c-Pd-Ni-P@a-Pd-Ni-P nanoplates can be tuned in the range from 9.47 to 38.61 at%. When used as a catalyst, the c-Pd-Ni-P@a-Pd-Ni-P nanoplates with 9.47 at% Ni exhibit excellent electrocatalytic activity toward ethanol oxidation, showing a high mass current density up to 3.05 A mg Pd −1 , which is 4.5 times that of the commercial Pd/C catalyst (0.68 A mg Pd −1 ).

Technical lignins, mostly generated as byproducts from the pulping industry, are highly abundant aromatic sources. However, they are underutilized due to their complexity, as well as structural alteration during chemical pulping processes. In-depth elucidation of technical lignins is becoming essential for their valorization in view of the lack of understanding of technical lignin structures. In this work, alkaline and kraft lignins were prepared and comparatively characterized by 2D HSQC NMR. By applying authenticated reference compounds, the phenylglycerol structures, characteristic of the cleavage of nonphenolic β-aryl ether by soda pulping, in the alkaline lignin were identified and quantified by 2D HSQC NMR. Phenylglycerol structures in alkaline lignin were estimated to be 8−14%, which was much higher than that in kraft lignin. This finding was supported by the results from model studies; i.e., the yield of the phenylglycerol product was 40% that obtained from the soda pulping treatment of a nonphenolic β-aryl ether compound while the yield of that from kraft treatment was lower than 5%. In addition, styryl ether structures from phenolic β-aryl ethers of alkaline lignin were also revealed by 2D NMR. These new findings will benefit the mechanistic understanding of lignin reactions and structural elucidation of technical lignins, which will provide useful information (or new insights) for the development of lignin valorization strategies.