The development of effective and stable electrocatalysts for the hydrogen evolution reaction (HER) in acidic electrolytes is a significant challenge. In this work, homogeneous Pt nanodendrites (Pt NDs) with a PtIr shell were successfully synthesized by a two-step wet chemical method. This open three-dimensional (3D) dendritic structure exhibited exceptional electrocatalytic characteristics, exposing as many active sites as feasible. Furthermore, by alloying Ir with Pt on the surface, catalytic activity was greatly enhanced while ensuring extremely high stability. Iridium surface-enriched platinum nanodendritic catalysts (Pt@PtIr NDs) outperformed the control samples and the commercial catalysts. In acidic HER test, Pt@PtIr NDs had a lower overpotential (22 mV) than Pt NDs (26 mV) and commercial Pt/C (31 mV) at 10 mA/cm², and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h, which was much superior to the performance of commercial Pt/C (10 h) under identical test conditions. This study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.

As efficient catalysts of electrochemical CO₂ reduction reaction (CO₂RR) towards multicarbon (C₂₊) products, Cu-based catalysts have faced the challenges of increasing the reactive activity and selectivity. Herein, we decorated the surface of Cu nanowires (Cu NWs) with a small amount of Au nanoparticles (Au NPs) by the homo-nucleation method. When the Au to Cu mass ratio is as little as 0.7 to 99.3, the gold-doped copper nanowires (Cu-Au NWs) could effectively improve the selectivity and activity of CO₂RR to C₂₊ resultants, with the Faradaic efficiency (FE) from 39.7% (Cu NWs) to 65.3%, and the partial current density from 7.0 (Cu NWs) to 12.1 mA/cm² under −1.25 V vs. reversible hydrogen electrode (RHE). The enhanced electrocatalytic performance could be attributed to the following three synergetic factors. The addition of Au nanoparticles caused a rougher surface of the catalyst, which allowed for more active sites exposed. Besides, Au sites generated *CO intermediates spilling over into Cu sites with the calculated efficiency of 87.2%, which are necessary for multicarbon production. Meanwhile, the interphase electron transferred from Cu to Au induced the electron-deficient Cu, which favored the adsorption of *CO to further generate multicarbon productions. Our results uncovered the morphology, tandem, and electronic effect between Cu NWs and Au NPs facilitated the activity and selectivity of CO₂RR to multicarbons.

Electrochemical conversion of carbon dioxide (CO₂) to higher-value products provides a forward-looking way to solve the problems of environmental pollution and energy shortage. However, the low solubility of CO₂ in aqueous electrolytes, sluggish kinetics, and low selectivity hamper the efficient conversion of CO₂. Here, we report a Au-based hybrid nanomaterial by modifying Au nanoparticles (NPs) with the macrocyclic molecule cucurbit[6]uril (Au@CB[6]). Au@CB[6] displays the optimal selectivity of CO, with the highest CO Faraday efficiency (FE_CO) reaching 99.50% at −0.6 V vs. reversible hydrogen electrode (RHE). The partial current density of CO formed by Au@CB[6] increases dramatically, as 3.18 mA/cm² at −0.6 V, which is more than ten times as that of oleylamine-coated Au NPs (Au@OAm, 0.31 mA/cm²). Operando electrochemical measurement combined with density functional theory (DFT) calculations reveals that CB[6] can gather CO₂ and lead the increased local CO₂ concentration near metal interface, which realizes significantly enhanced electrochemical CO₂ reduction reaction (CO₂RR) performance.

Metal nanomaterials have exhibited excellent performance in electrocatalytic applications, but they still face the problems of poor stability and limited regulation strategies. It is an efficient strategy for greatly enhanced catalytic activity and stability by introducing a second component. In this review, we provide the sketch for the combination of metal nanomaterials and cucurbit[n]urils (CB[n]s) in electrocatalytic applications. CB[n]s are a series of macrocycles with rigid structure, high stability, and function groups for coordinating with metal sites, which make them promising to stabilize and modulate the metal nanomaterials for ideal performance. The discussion classifies the roles of CB[n]s, involving CB[n]s as protecting agents, CB[n]-based supramolecular self-assemblies and CB[n]s as the precursor for the preparation of N-doped holy carbon matrix. Various metal nanocatalysts including metal (Pt, Ir, Pd, Ru, Au) nanoparticles, metal (Fe, Co, Ni) single-atoms, and transition metal carbides (TMCs) have been integrated with CB[n] orCB [n]-derived carbon matrix. These nanomaterials show superior activity and stability in multiple electrocatalytic reactions, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO2RR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR). Furthermore, a few metal-CB[n] composites can become bifunctional catalysts applied in the overall water splitting and fuel cell. It is surprising that the activity of CB[n]-based nanocatalysts is comparable with that of commercial catalyst, and the stability is even better. The experimental analysis together with the density functional theory (DFT) calculations verifies that the improvement can be attributed to the interaction between the metal nanocrystal and CB[n]s as well as the characteristic stability of CB[n]s. Finally, we talk about the challenges and opportunities for the cucurbit[n]uril-based electrocatalysis. This review provides an impressive strategy to obtain welldefined metal nanomaterials constructed with CB[n]s with enhanced performance, and expects that such a strategy will develop more efficient catalysts for a broader range of electro-applications.

Pd nanocubes (NCs) enclosed by six {100} facets are fascinating model materials for both fundamental studies and practical applications. However, the only available method to prepare well-defined sub-10 nm Pd NCs was developed by Xia et al. more than 10 years ago, unavoidably using polyvinylpyrrolidone (PVP) polymer to prevent particle aggregation. The strongly adsorbed PVP extremely deteriorates the catalysts' efficiency because of the high coverage of accessible surface-active sites. Numerous efforts have been devoted to replacing PVP with weaker capping agents but with limited progress predominately due to the difficulties in tuning the growth kinetics of Pd NCs. For the first time, we report that macrocycle cucurbit[6]uril (CB[6]) can replace PVP in the synthesis of Pd NCs by dedicatedly controlling the growth parameters. CB[6] capped Pd NCs showed 1.1–1.5 times increased specific surface area compared to the surfactant-free commercial Pd catalysts. Moreover, X-ray photoelectron spectroscopy demonstrated the modified electronic structure of Pd NCs through the carbonyl group of CB[6]. Consequently, compared to the commercial catalysts, the obtained Pd NCs exhibited 7 times higher current density towards ethanol oxidation reaction. Remarkably, after 17 h of continuous work, it reduced deactivation by up to 1–4 orders of magnitude.

Anisotropic Pd nanoparticles with highly branched morphologies are urgently needed as building blocks for nanoscale devices, catalysts, and sensing materials owing to their novel structures and unique physicochemical properties. However, realizing size control and branch manipulation for these materials is very challenging. In this study, we develop a facile ultrafine Cu seed-mediated approach in the aqueous phase to produce novel Pd–Cu trigonal hierarchical nanoframes (THNFs). The main branch of most of the obtained nanocrystals is tripod-like, with advanced branches along the arms as frame units having self-similarity. In this method, the size of the Pd–Cu THNFs can be flexibly controlled by manipulating the nucleation involving the sub-3 nm Cu seeds. These Pd–Cu THNFs outperform Pd black with regard to their ethanol-oxidation performance, having a specific activity and mass activity 9.7 and 6.6 times higher, respectively. This research provides a versatile ultrafine seed-mediated approach for producing size-controlled anisotropic bimetallic nanoframes.