Recent Advances in Amino-Based Molecules Assisted Control of Noble-Metal Electrocatalysts

High-entropy alloy nanopatterns by prescribed metallization of DNA origami templates

High-entropy multimetallic nanopatterns with controlled morphology, composition and uniformity hold great potential for developing nanoelectronics, nanophotonics and catalysis. Nevertheless, the lack of general methods for patterning multiple metals poses a limit. Here, we develop a DNA origami-based metallization reaction system to prescribe multimetallic nanopatterns with peroxidase-like activities. We find that strong coordination between metal elements and DNA bases enables the accumulation of metal ions on protruding clustered DNA (pcDNA) that are prescribed on DNA origami. As a result of the condensation of pcDNA, these sites can serve as nucleation site for metal plating. We have synthesized multimetallic nanopatterns composed of up to five metal elements (Co, Pd, Pt, Ag and Ni), and obtained insights on elemental uniformity control at the nanoscale. This method provides an alternative pathway to construct a library of multimetallic nanopatterns.

Dual Function of 4-Aminothiophene in Surface-Enhanced Raman Scattering Application as an Internal Standard and Adsorbent for Controlling Au Nanocrystal Morphology

The sensitivity and quantitative accuracy of surface-enhanced Raman scattering (SERS) are the main factors that restrict its application. Here, novel Au nanoscale convex polyhedrons (Au NCPs) were designed and fabricated to solve these problems via an embedded standard, including eight pods and six small protrusions. Spherical Au seeds regrew into different sizes of Au NCPs with a face-centered cubic structure. This morphology is due to the dual mechanism of the 4-aminothiophene (4-ATP) molecule that serves as an internal standard and a surface ligand regulator combined with the regulatory role of hexadecyl trimethyl ammonium chloride. The results show that Au NCPs were enclosed by high-index {12 9 1} facets, which greatly improved the local plasma resonance and reduced the lowest SERS detectable concentration of pyrene in standard seawater to 0.5 nM. An effective reference was produced by embedding 4-ATP with a relative standard deviation value less than 2.97% (in the same batch) and 3.92% (between different batches). Our research offers a new strategy for morphological regulation of metal nanocrystals, which is useful for the preparation of highly sensitive SERS substrates and trace analysis.

Ultra-trace and quantitative SERS detection of polycyclic aromatic hydrocarbons based on Au nanoscale convex polyhedrons with embedded probe molecules

Surface-enhanced Raman scattering (SERS) has great potential for the detection of marine pollutants, but it is still restricted in ultra-trace and quantitative analysis. Here, a strategy for the detection of polycyclic aromatic hydrocarbons (PAHs) was proposed based on Au nanoscale convex polyhedrons (Au NCPs) coated with high-energy facets and embedded with 4-ATP as a probe molecule. Au NCPs acted as SERS substrates and led to limits of detection (LODs) for six common PAHs that reached 0.01 nM. Using internal calibration, the relative standard deviations (RSD) of the spectral stability and reproducibility were as low as 3.36% and 5.11%, respectively. The maximum mean relative errors (AREs) of the predicted and true values were 6.28%. The results indicate that the resulting Au NCPs improved the ultra-trace and quantitative detection of SERS, thus suggesting that the Au NCPs have practical application value in SERS.

One-Pot Synthesis of Pt Nanobowls Assembled from Ultrafine Nanoparticles for Methanol Oxidation Reaction

Simultaneously engineering a bowl-like and ultrafine nano-size structure offers an attractive route to not only increase the utilization efficiency of noble metals, the specific surface areas and the availability of active sites, but also boost the structural robustness and long-term stability. However, a great challenge remains in terms of the methods of synthesis. Herein, we report a facile one-pot hydrothermal method for the preparation of hollow porous Pt nanobowls (NBs) assembled from ultrafine particles. N,N'-methylenebisacrylamide (MBAA) acts as a structure-directing agent that forms a self-template with Pt ions and drives the nucleation and assembly of Pt metals, resulting in the fabrication of Pt NBs from ultrafine particles. By virtue of their unique structure and morphology, the optimized Pt NBs exhibited enhanced electrocatalytic methanol oxidation reaction (MOR) activity with 3.1-fold greater mass activity and 2.6-fold greater specific activities compared with those of commercial Pt black catalysts, as well as excellent stability and anti-poisoning ability.

Boosting Electrocatalytic Oxygen Evolution over Ce-Co9 S8 Core-Shell Nanoneedle Arrays by Electronic and Architectural Dual Engineering

An dual electronic and architectural engineering strategy is a good way to rationally design earth-abundant and highly efficient electrocatalysts of the oxygen evolution reaction (OER) for sustainable hydrogen-based energy devices. Here, a Ce-doped Co₉ S₈ core-shell nanoneedle array (Ce-Co₉ S₈ @CC) supported on a carbon cloth has been designed and developed to accelerate the sluggish kinetics of the OER. Profiting from valance alternative Ce doping, a fine core-shell structure and vertically aligned nanoneedle arrayed architecture, Ce-Co₉ S₈ @CC integrates modulated electronic structure, highly exposed active sites, and multidimensional mass diffusion channels; together, these afford a favorable catalyzed OER. Ce-Co₉ S₈ @CC exhibits remarkable performance in the OER in an alkaline medium, where the overpotential requires only 242 mV to deliver a current density of 10 mA cm^-2 for the OER; this is 70 mV superior to that of Ce-free Co₉ S₈ catalyst and other counterparts. Good stability and impressive selectivity (nearly 100 % Faradic efficiency) are also demonstrated. When integrated into a two-electrode OER//HER electrolyzer, the as-prepared Ce-Co₉ S₈ @CC displays a low operation potential of 1.54 V at 10 mA cm^-2 and long-term stability, thus demonstrating great potential for economical water electrolysis.

Carbon Nanotubes Interconnected NiCo Layered Double Hydroxide Rhombic Dodecahedral Nanocages for Efficient Oxygen Evolution Reaction

Proper control of a 3d transition metal-based catalyst with advanced structures toward oxygen evolution reaction (OER) with a more feasible synthesis strategy is of great significance for sustainable energy-related devices. Herein, carbon nanotube interconnected NiCo layered double hydroxide rhombic dodecahedral nanocages (NiCo-LDH RDC@CNTs) were developed here with the assistance of a feasible zeolitic imidazolate framework (ZIF) self-sacrificing template strategy as a highly efficient OER electrocatalyst. Profited by the well-fined rhombic dodecahedral nanocage architecture, CNTs’ interconnected characteristic and structural feature of the vertically aligned nanosheets, the as-synthesized NiCo-LDH RDC@CNTs integrated large exposed active surface areas, enhanced electron transfer capacity and multidimensional mass diffusion channels, and thereby collaboratively afforded the remarkable electrocatalytic performance of the OER. Specifically, the designed NiCo-LDH RDC@CNTs exhibited a distinguished OER activity, which only required a low overpotential of 255 mV to reach a current density of 10 mA cm⁻² for the OER. For the stability, no obvious current attenuation was detected, even after continuous operation for more than 27 h. We certainly believe that the current extraordinary OER activity combined with the robust stability of NiCo-LDH RDC@CNTs enables it to be a great candidate electrocatalyst for economical and sustainable energy-related devices.

Engineering Heterostructured Pd-Bi2Te3 Doughnut/Pd Hollow Nanospheres for Ethylene Glycol Electrooxidation

The electrooxidation of ethylene glycol (EG) is of vital significance for the conversion from biomass energy into electrical energy via direct fuel cells. However, the EG oxidation reaction (EGOR) suffers from poor efficiency due to the limitation of high-performance electrocatalysts for cleaving the C-C bonds. Herein, this limitation is successfully addressed by fabricating the doughnut-shaped Pd-Bi₂Te₃ heterostructured catalyst. Notably, the heterojunction Pd-Bi₂Te₃ nanocatalyst has been demonstrated to be highly active toward the EGOR with superb activity and durability, in which a mass activity as high as 2420.8 mA mg^-1 is achieved in alkaline media, being 1.7 times higher than that of the commercial Pd/C catalyst. Upon combination of experimental results with mechanism studies, it is indicated that the remarkable EGOR performance is attributed to the enlarged active areas that stemmed from the doughnut-like structure, as well as the strong synergistic effect from Pd-Bi₂Te₃ and Pd. More importantly, the highly electroactive Pd-Bi₂Te₃ can accelerate charge transfer and boost the oxidation of CO-like intermediates, which are conducive to the enhancement in electrochemical stability.

Synthesis of Pd nanorod arrays on Au nanoframes for excellent ethanol electrooxidation

Au-Pd hollow nanostructures have attracted a lot of attention because of their excellent ethanol electrooxidation performance. Herein, we report a facile preparation of Au nanoframe@Pd array electrocatalysts in the presence of cetylpyridinium chloride. The reduced Pd atoms were directed to mainly deposit on the surface of the Au nanoframes in the form of rods, leading to the formation of Au nanoframe@Pd arrays with a super-large specific surface area. The red shift and damping of the plasmon peak were ascribed to the deposition of the Pd arrays on the surface of the Au nanoframes and nanobipyramids, which was verified by electrodynamic simulations. Surfactants, temperature and reaction time determine the growth process and thereby the architecture of the obtained Au-Pd hollow nanostructures. Compared with the Au nanoframe@Pd nanostructures and Au nanobipyramid@Pd arrays, the Au nanoframe@Pd arrays exhibit an enhanced electrocatalytic performance towards ethanol electrooxidation due to an abundance of catalytic active sites. The Au NF@Pd arrays display 4.1 times higher specific activity and 13.7 times higher mass activity than the commercial Pd/C electrocatalyst. Moreover, the nanostructure shows improved stability towards the ethanol oxidation reaction. This study enriches the manufacturing technology to increase the active sites of noble metal nanocatalysts and promotes the development of direct ethanol fuel cells.

Origins of Electron-Transfer Regime in Persulfate-Based Nonradical Oxidation Processes

Persulfate-based nonradical oxidation processes (PS-NOPs) are appealing in wastewater purification due to their high efficiency and selectivity for removing trace organic contaminants in complicated water matrices. In this review, we showcased the recent progresses of state-of-the-art strategies in the nonradical electron-transfer regimes in PS-NOPs, including design of metal and metal-free heterogeneous catalysts, in situ/operando characterization/analytical techniques, and insights into the origins of electron-transfer mechanisms. In a typical electron-transfer process (ETP), persulfate is activated by a catalyst to form surface activated complexes, which directly or indirectly interact with target pollutants to finalize the oxidation. We discussed different analytical techniques on the fundamentals and tactics for accurate analysis of ETP. Moreover, we demonstrated the challenges and proposed future research strategies for ETP-based systems, such as computation-enabled molecular-level investigations, rational design of catalysts, and real-scenario applications in the complicated water environment. Overall, this review dedicates to sharpening the understanding of ETP in PS-NOPs and presenting promising applications in remediation technology and green chemistry.

Electronic structure optimization boosts Pd nanocrystals for ethanol electrooxidation realized by Te doping

Te doping greatly modifies the electronic structure of Pd and promotes the electrocatalytic performance towards EOR.

Evolution of PtCu tripod nanocrystals to dendritic triangular nanocrystals and study of the electrochemical performance to alcohol electrooxidation

In the field of catalysis, the design and construction of nanomaterials is an efficient way to optimize the catalytic activity of catalysts. This study presents the synthesis of PtCu tripod nanocrystals with branching structures and high purity prepared using a simple hydrothermal method. The dendritic PtCu triangular nanocrystals were successfully synthesized by regulating the amount of I^- ions to achieve different degrees of branching on PtCu nanocrystals, and the process was systematically studied and analyzed. Meanwhile, dumbbell nanocrystals of PtCu were successfully synthesized through slight adjustments to synthesis conditions. In electrochemical tests, the obtained dendritic PtCu triangular nanocrystals exhibited prominent electrocatalytic activity and long-term stability for ethylene glycol, methanol, and ethanol oxidation reactions due to the unique nanostructures as well as alloyed virtue, and were much better than commercial Pt/C. In addition, this study provides a general strategy for designing novel branched Pt-based nanomaterials with high electrocatalytic performance.

Bifunctional Pd@RhPd Core-Shell Nanodendrites for Methanol Electrolysis

Methanol electrolysis is a promising strategy to achieve energy-saving and efficient electrochemical hydrogen (H₂) production. In this system, the advanced electrocatalysts with high catalytic performance for both the methanol oxidation reaction (MOR) and hydrogen evolution reaction (HER) are highly desirable. Inspired by the complementary catalytic properties of rhodium (Rh) and palladium (Pd) for MOR and HER, herein, several Pd core-RhPd alloy shell nanodendrites (Pd@RhPd NDs) are synthesized through the galvanic replacement reaction between Pd nanodendrites (Pd NDs) and rhodium trichloride. For MOR, Pd@RhPd NDs exhibit Rh content-determined catalytic activity, in which Pd@Rh_0.07Pd NDs have an optimal combination of oxidation potential and oxidation current due to the synergistic catalytic process of Pd/Rh double active sites. For HER, the introduction of Rh greatly improves the catalytic activity of Pd@RhPd NDs compared to that of Pd NDs, suggesting that Rh is the main activity site for HER. Unlike MOR, however, the HER activity of Pd@RhPd NDs is not sensitive to the Rh content. Using Pd@Rh_0.07Pd NDs as robust bifunctional electrocatalysts, the as-constructed two-electrode methanol electrolysis cell shows a much lower voltage (0.813 V) than that of water electrolysis (1.672 V) to achieve electrochemical H₂ production at 10 mA cm^-2, demonstrating the application prospect of methanol electrolysis for H₂ production.

Cyanogroup functionalized sub-2 nm ultrafine Pt nanonetworks reinforce electrocatalytic hydrogen evolution in a broad pH range

Cyanogroup functionalized Pt ultrafine nanonetworks are synthesized via a facile one-pot oil bath heating method, and exhibit excellent HER performance in a broad pH range.