In contrast to the conventional etching that makes nanoparticles rounder and our previous sharpening etching mode that causes serrated edges, here, we developed a new boring etching mode that targets the faces of Au nanoplates to make holes. The critical factors are the pre-incubation step with the ligand 2-mercapto-5-benzimidazolecarboxylic acid (MBIA) and the subsequent removal of excess ligands in the solution. Thus, etching is focused onto the few sites with initial loss of ligands, which cannot be quickly replaced. The choice of ligand MBIA is also of importance, as it carries negative charge and repels each other. Its inability of forming a dense layer probably plays a critical role in the site-selectivity for faces, because ligands at the higher curvature edges and corners are expected to have less repulsion. The etching results from the comproportionation reaction between Au³⁺ and Au⁰ in the nanoplates, where Br⁻ coordination to Au and the extra stabilization from cetyltrimethylammonium bromide (CTAB) are essential. We believe that the ability of boring holes is an important tool for future synthetic designs.

We show that through strong ligand mediated interfacial energy control between Au seeds and the deposited Au, the non-wetting growth of Au on Au seeds led to the formation homometallic core–satellite nanostructures. To modulate the intraparticle plasmonic coupling between the core and the satellites, the number and size of the Au satellites, and their inter-island distances were continuously tuned by varying the growth kinetics. As a result of the precise structural control, the plasmonic absorptions of the core–satellite nanostructures were tuned from visible to near-infrared (NIR) spectral range, and the extent of spectral modulation (500–1300 nm) is among the best of the literature methods. This synthetic advance enriches the toolbox for nanosynthesis and points to a new direction in the exploration of sophisticated functional designs.

Hollow nanostructures with structural advantages have been widely exploited as catalysts in electrochemical reactions. However, there are only limited strategies for constructing hollow Pd-based nanostructures. In this work, Pd₄S hollow nanospheres (Pd₄S HNSs) are synthesized with a facile wet-chemical method via a self-templating process. Intermediate Pd-L-cysteine solid nanospheres (SNSs) were firstly obtained by the coordination of L-cysteine with Pd²⁺, and then in situ converted to hollow nanospheres in the following reduction process. The formation mechanism of the Pd₄S HNSs was studied, and the size of the Pd₄S HNSs can be readily adjusted by tuning the size of the SNSs. The hollow morphology would help the exposure of active sites and the prevention of aggregation during the catalytic reactions. As a result, the Pd₄S HNSs exhibit improved catalytic performances in the oxygen reduction reactions, with a half-wave potential of 0.913 V vs. reversible hydrogen electrode (RHE) and impressive stability in the accelerated durability test.