Crystal-Phase-Engineered High-Entropy Alloy Aerogels for Enhanced Ethylamine Electrosynthesis from Acetonitrile.

Crystal-phase engineering that promotes the rearrangement of active atoms to form new structural frameworks achieves excellent result in the field of electrocatalysis and optimizes the performance of various electrochemical reactions. Herein, for the first time, it is found that the different components in metallic aerogels will affect the crystal-phase transformation, especially in high-entropy alloy aerogels (HEAAs), whose crystal-phase transformation during annealing is more difficult than medium-entropy alloy aerogels (MEAAs), but they still show better electrochemical performance. Specifically, PdPtCuCoNi HEAAs with the parent phase of face-centered cubic (FCC) PdCu possess excellent 89.24% of selectivity, 746.82 mmol h-1 g-1 cat. of yield rate, and 90.75% of Faraday efficiency for ethylamine during acetonitrile reduction reaction (ARR); while, maintaining stability under 50 h of long-term testing and ten consecutive electrolysis cycles. The structure-activity relationship indicates that crystal-phase regulation from amorphous state to FCC phase promotes the atomic rearrangement in HEAAs, thereby optimizing the electronic structure and enhancing the adsorption strength of reaction intermediates, improving the catalytic performance. This study provides a new paradigm for developing novel ARR electrocatalysts and also expands the potential of crystal-phase engineering in other application areas.

Amorphous-crystalline RuTi nanosheets enhancing OH species adsorption for efficient hydrogen oxidation catalysis.

Anion exchange membrane fuel cells are a potentially cost-effective energy conversion technology, however, the electrocatalyst for the anodic hydrogen oxidation reaction (HOR) suffers from sluggish kinetics under alkaline conditions. Herein, we report that Ru-based nanosheets with amorphous-crystalline heterointerfaces of Ru and Ti-doped RuO2 (a/c-Ru/Ti-RuO2) can serve as a highly efficient HOR catalyst with a mass activity of 4.16 A mgRu-1, which is 19.8-fold higher than that of commercial Pt/C. Detailed characterization studies show that abundant amorphous-crystalline heterointerfaces of a/c-Ru/Ti-RuO2 nanosheets provide oxygen vacancies and unsaturated coordination bonds for balancing adsorption of hydrogen and hydroxyl species on Ru active sites to elevate HOR activity. Moreover, Ti doping can facilitate CO oxidation, leading to enhanced strength to CO poisoning. This work provides a strategy for enhancing alkaline HOR performance over Ru-based catalysts with heteroatom and heterointerface dual-engineering, which will attract immediate interest in chemistry, materials science and beyond.

Implanting oxophilic metal in PtRu nanowires for hydrogen oxidation catalysis.

Bimetallic PtRu are promising electrocatalysts for hydrogen oxidation reaction in anion exchange membrane fuel cell, where the activity and stability are still unsatisfying. Here, PtRu nanowires were implanted with a series of oxophilic metal atoms (named as i-M-PR), significantly enhancing alkaline hydrogen oxidation reaction (HOR) activity and stability. With the dual doping of In and Zn atoms, the i-ZnIn-PR/C shows mass activity of 10.2 A mgPt+Ru-1 at 50 mV, largely surpassing that of commercial Pt/C (0.27 A mgPt-1) and PtRu/C (1.24 A mgPt+Ru-1). More importantly, the peak power density and specific power density are as high as 1.84 W cm-2 and 18.4 W mgPt+Ru-1 with a low loading (0.1 mg cm-2) anion exchange membrane fuel cell. Advanced experimental characterizations and theoretical calculations collectively suggest that dual doping with In and Zn atoms optimizes the binding strengths of intermediates and promotes CO oxidation, enhancing the HOR performances. This work deepens the understanding of developing novel alloy catalysts, which will attract immediate interest in materials, chemistry, energy and beyond.

Facilitating alkaline hydrogen evolution reaction on the hetero-interfaced Ru/RuO2 through Pt single atoms doping.

Exploring an active and cost-effective electrocatalyst alternative to carbon-supported platinum nanoparticles for alkaline hydrogen evolution reaction (HER) have remained elusive to date. Here, we report a catalyst based on platinum single atoms (SAs) doped into the hetero-interfaced Ru/RuO2 support (referred to as Pt-Ru/RuO2), which features a low HER overpotential, an excellent stability and a distinctly enhanced cost-based activity compared to commercial Pt/C and Ru/C in 1 M KOH. Advanced physico-chemical characterizations disclose that the sluggish water dissociation is accelerated by RuO2 while Pt SAs and the metallic Ru facilitate the subsequent H* combination. Theoretical calculations correlate with the experimental findings. Furthermore, Pt-Ru/RuO2 only requires 1.90 V to reach 1 A cm-2 and delivers a high price activity in the anion exchange membrane water electrolyzer, outperforming the benchmark Pt/C. This research offers a feasible guidance for developing the noble metal-based catalysts with high performance and low cost toward practical H2 production.

AIS-based operational phase identification using Progressive Ablation Feature Selection with machine learning for improving ship emission estimates.

The work status of ships' engines and boilers has a significant impact on emission estimates, which are closely related to ships' operational phases. To improve the accuracy of emission estimates, this study proposed a machine learning-based classification model for identifying operational phases. We proposed 12 operational phase relevance features by analyzing motion behavior-related and geospatial characteristics-related features from the Automatic Identification System (AIS) data from the two bulk carriers. The random forest (RF) model showed the best performance in identifying one of the bulk carrier's operational phases among the five machine models, with the accuracy, F1score and Area Under Curve (AUC) of 96.66%, 93.34% and 99.93%, respectively. By adopting the Progressive Ablation Feature Selection (PAFS) method with RF, the number of features was reduced from 12 to 8, and the accuracy (96.38%), F1score (92.70%), and AUC (98.81%) were almost same with that obtained from all 12 features. Additionally, the effectiveness of the RF model was validated on the other bulk carriers. Compared with the traditional algorithms, the RF model showed better performance in ship operational phase identification and improved the average accuracy of NOx emission estimation for the main engine and auxiliary engine by 57.83% and 93.89%, respectively, under different operational phases. These results provide the basis for port traffic management and ship emission control.Implications: A new ship operational phase identification approach was proposed in this study. If the proposed approach is adopted by International Maritime Organization, it will improve the accuracy of ship emission estimates and bring new insights into global shipping greenhouse gas (GHG) emissions and their impact on global change. The port authorities could benefit from the proposed approach, which can be extended to ship types with similar behavior to bulk carriers, such as containers and general cargoes. This can reveal patterns of ship behavior in specific areas, which helps to identify potential collision risks, channel blockages, and other safety issues and take appropriate management measures to ensure the safe operation of the port. The proposed approach can help shipping companies to accurately estimate the GHG emissions of their fleets and to accurately predict carbon tax costs. Base on that, carbon emissions and carbon tax burden can be reduced by adopting corresponding management control measures.

3D Noble-Metal Nanostructures Approaching Atomic Efficiency and Atomic Density Limits.

Noble metals have been widely used in catalysis, however, the scarcity and high cost of noble metal motivate researchers to balance the atomic efficiency and atomic density, which is formidably challenging. This article proposes a robust strategy for fabricating 3D amorphous noble metal-based oxides with simultaneous enhancement on atomic efficiency and density with the assistance of atomic channels, where the atomic utilization increases from 18.2% to 59.4%. The unique properties of amorphous bimetallic oxides and formation of atomic channels have been evidenced by detailed experimental characterizations and theoretical simulations. Moreover, the universality of the current strategy is validated by other binary oxides. When Cu2IrOx with atomic channels (Cu2IrOx-AE) is used as catalyst for oxygen evolution reaction (OER), the mass activity and turnover frequency value of Cu2IrOx-AE are 1-2 orders of magnitude higher than CuO/IrO2 and Cu2IrOx without atomic channels, largely outperforming the reported OER catalysts. Theoretical calculations reveal that the formation of atomic channels leads to various Ir sites, on which the proton of adsorbed *OH can transfer to adjacent O atoms of [IrO6]. This work may attract immediate interest of researchers in material science, chemistry, catalysis, and beyond.

Continuous Phase Regulation of a Pd-Te Hexagonal Nanoplate Library.

Phase regulation of noble metal-based nanomaterials provides a promising strategy for boosting the catalytic performance. However, realizing the continuous phase modulation in two-dimensional structures and unveiling the relevant structure-performance relationship remain significant challenges. In this work, we present the first example of continuous phase modulation in a library of Pd-Te hexagonal nanoplates (HNPs) from cubic-phase Pd4Te, rhombohedral-phase Pd20Te7, rhombohedral-phase Pd8Te3, and hexagonal-phase PdTe to hexagonal-phase PdTe2. Notably, the continuous phase regulation of the well-defined Pd-Te HNPs enables the successful modulation of the distance between adjacent Pd active sites, triggering an exciting way for tuning the relevant catalytic reactions intrinsically. The proof-of-concept oxygen reduction reaction (ORR) experiment shows a Pd-Pd distance-dependent ORR performance, where the hexagonal-phase PdTe HNPs present the best electrochemical performance in ORR (mass activity and specific activity of 1.02 A mg-1Pd and 1.83 mA cm-2Pd at 0.9 V vs RHE). Theoretical investigation reveals that the increased Pd-Pd distance relates to the weak *OH adsorption over Pd-Te HNPs, thus contributing to the remarkable ORR activity of PdTe HNPs. This work advances the phase-controlled synthesis of noble metal-based nanostructures, which gives huge impetus to the design of high-efficiency nanomaterials for diverse applications.

Defective ZnIn2S4 Nanosheets for Visible-Light and Sacrificial-Agent-Free H2O2 Photosynthesis via O2/H2O Redox.

H2O2 photosynthesis has attracted great interest in harvesting and converting solar energy to chemical energy. Nevertheless, the high-efficiency process of H2O2 photosynthesis is driven by the low H2O2 productivity due to the recombination of photogenerated electron-hole pairs, especially in the absence of a sacrificial agent. In this work, we demonstrate that ultrathin ZnIn2S4 nanosheets with S vacancies (Sv-ZIS) can serve as highly efficient catalysts for H2O2 photosynthesis via O2/H2O redox. Mechanism studies confirm that Sv in ZIS can extend the lifetimes of photogenerated carriers and suppress their recombination, which triggers the O2 reduction and H2O oxidation to H2O2 through radical initiation. Theoretical calculations suggest that the formation of Sv can strongly change the coordination structure of ZIS, modulating the adsorption abilities to intermediates and avoiding the overoxidation of H2O to O2 during O2/H2O redox, synergistically promoting 2e- O2 reduction and 2e- H2O oxidation for ultrahigh H2O2 productivity. The optimal catalyst displays a H2O2 productivity of 1706.4 µmol g-1 h-1 under visible-light irradiation without a sacrificial agent, which is ∼29 times higher than that of pristine ZIS (59.4 µmol g-1 h-1) and even much higher than those of reported photocatalysts. Impressively, the apparent quantum efficiency is up to 9.9% at 420 nm, and the solar-to-chemical conversion efficiency reaches ∼0.81%, significantly higher than the value for natural synthetic plants (∼0.10%). This work provides a facile strategy to separate the photogenerated electron-hole pairs of ZIS for H2O2 photosynthesis, which may promote fundamental research on solar energy harvest and conversion.

Structurally-Distorted RuIr-Based Nanoframes for Long-Duration Oxygen Evolution Catalysis.

Oxygen evolution reaction (OER) plays a key role in proton exchange membrane water electrolysis (PEMWE), yet the electrocatalysts still suffer from the disadvantages of low activity and poor stability in acidic conditions. Here, a new class of CdRu2 IrOx nanoframes with distorted structure for acidic OER is successfully fabricated. Impressively, CdRu2 IrOx displays an ultralow overpotential of 189 mV and an ultralong stability of 1500 h at 10 mA cm⁻2 toward OER in 0.5 M H2 SO4 . Moreover, a PEMWE using the distorted CdRu2 IrOx can be steadily operated at 0.1 A cm⁻2 for 90 h. Microstructural analyses and X-ray absorption spectroscopy (XAS) demonstrate that the synergy between Ru and Ir in CdRu2 IrOx induces the distortion of Ru-O, Ir-O, and Ru-M (M = Ru, Ir) bonds. In situ XAS indicates that the applied potential leads to the deformation octahedral structure of RuOx /IrOx and the formation of stable Ru5+ species for OER. Theoretical calculations also reveal that the distorted structures can reduce the energy barrier of rate-limiting step during OER. This work provides an efficient strategy for constructing structural distortion to achieve significant enhancement on the activity and stability of OER catalysts.

Seasonal dynamics of coastal pollution migration in open waters with intensive marine ranching.

Mariculture activities have been recognized as one of the major sources of contamination for marine pollutants, such as the excessive discharging of nitrogen and phosphate. The fully understanding of the pollutants emission and transportation is crucial for coastal environment management. However, the influence of such highly dynamic coastal process on the pollutant migration remain unclear, such as the effects of coastal seasonal hydrodynamics on the dissolved pollutant transportation, especially under intensive marine ranching activities in open waters. This study investigated the seasonal transport mechanisms of pollutants released from three typical mariculture methods (floating raft, cage and bottom pond) in the Wangjia Island (WJ), Yellow Sea, China. We have conducted three field surveys to monitor the coastal dynamics and measure the distribution of dissolved pollutants in the ranching area. Results from these field surveys show that the WJ and adjacent area experienced significant degradation in terms of water quality with the development of regional marine ranching. The average of calculated index for eutrophication Ei increases from 0.12 in the non-farming area to 0.78 in the farming area. In order to delineate the impacts area of pollutant transport associated with these highly dynamics of water exchange, a Eulerian passive tracer-tracking module is applied to simulate the pollutant transport processes based on a field scale three-dimensional Finite Volume Coastal Ocean Model (FVCOM). Then after, the impacts of barotropic and baroclinic coastal dynamics on the migration of dissolved pollutants were evaluated. The transport of pollutants was greatly influenced by the different farming modes. The travel distance of pollutants released from the bottom pond farming mode was limited, whereas pollutants from the surface-farming methods were transported over a longer distance. In this study, there are three folders of finding: 1) The migration direction varies with seasons, with a landward direction in winter and an offshore direction in summer; 2) In winter, strong wind (wind speed over 10 m/s) is the dominant factor for water exchange, which is conducive to the dispersion of pollutants in the study area. However, in summer, the thermal stratification controls pollutant migration; 3) The results of breakthrough time illustrate that the pollutants travelled slower during summer, especially for pollutants discharged from the bottom pond farming method. In summary, this study demonstrates that even in open waters with stronger water exchange capacity, the pollutants from intensive marine ranching can still increase the risk of eutrophication. The finding of this study has important implications for the management and regulation of offshore aquaculture activities, particularly for mitigating pollutants from marine ranching.

Platinum-Lead-Bismuth/Platinum-Bismuth Core/Shell Nanoplate Achieves Complete Dehydrogenation Pathway for Direct Formic Acid Oxidation Catalysis.

Designing platinum (Pt)-based formic acid oxidation reaction (FAOR) catalysts with high performance and high selectivity of direct dehydrogenation pathway for direct formic acid fuel cell (DFAFC) is desirable yet challenging. Herein, we report a new class of surface-uneven PtPbBi/PtBi core/shell nanoplates (PtPbBi/PtBi NPs) as the highly active and selective FAOR catalysts, even in the complicated membrane electrode assembly (MEA) medium. They can achieve unprecedented specific and mass activities of 25.1 mA cm-2 and 7.4 A mgPt-1 for FAOR, 156 and 62 times higher than those of commercial Pt/C, respectively, which is the highest for a FAOR catalyst by far. Simultaneously, they show highly weak adsorption of CO and high dehydrogenation pathway selectivity in the FAOR test. More importantly, the PtPbBi/PtBi NPs can reach the power density of 161.5 mW cm-2, along with a stable discharge performance (45.8% decay of power density at 0.4 V for 10 h), demonstrating great potential in a single DFAFC device. The in situ Fourier transform infrared spectroscopy (FTIR) and X-ray absorption spectroscopy (XAS) results collectively reveal a local electron interaction between PtPbBi and PtBi. In addition, the high-tolerance PtBi shell can effectively inhibit the production/adsorption of CO, resulting in the complete presence of the dehydrogenation pathway for FAOR. This work demonstrates an efficient Pt-based FAOR catalyst with 100% direct reaction selectivity, which is of great significance for driving the commercialization of DFAFC.

Trace Lattice S Inserted RuO2 Flexible Nanosheets for Efficient and Long-Term Acidic Oxygen Evolution Catalysis.

Pursuing highly active and long-term stable ruthenium (Ru) based oxygen evolution reaction (OER) catalyst for water electrolysis under acidic conditions is of great significance yet a tremendous challenge to date. To solve the problem of serious Ru corrosion in an acid medium, the trace lattice sulfur (S) inserted RuO2 catalyst is prepared. The optimized catalyst (Ru/S NSs-400) has shown a record stability of 600 h for the solely containing Ru (iridium-free) nanomaterials. In the practical proton exchange membrane device, the Ru/S NSs-400 can even sustain more than 300 h without obvious decay at the high current density of 250 mA cm-2 . The detailed investigations reveal that S doping not only changes the electronic structure of Ru via forming RuS coordination for high adsorption of reaction intermediates but also stabilizes Ru from over-oxidation. This strategy is also effective for improving the stability of commercial Ru/C and homemade Ru-based nanoparticles. This work offers a highly effective strategy to design high-performance OER catalysts for water splitting and beyond.

Alkylamine-Confined Thickness-Tunable Synthesis of Co(OH)2-CoO Nanosheets toward Oxygen Evolution Catalysis.

Thickness regulation of transition metal hydroxides/oxides nanosheets with superior catalytic properties represents a promising strategy to enhance catalytic performance, but it remains an enormous challenge to achieve precise control, especially when it comes to the ultrathin limit (several atomic layers). In this work, a facile strategy of alkylamine-confined growth is proposed for the synthesis of thickness-tunable metal hydroxide/oxide nanosheets. Specifically, ultrathin cobalt hydroxide and cobaltous oxide hybrid (Co(OH)2-CoO) nanosheets (Co-O NSs) with a thickness in the range of 2-6 nm (5-13 atomic layers) are synthesized by using alkylamines with different carbon chain lengths as the ligand to modulate vertical coordination ability. Co-O NSs with a thickness of 2 nm (Co-O NSs-2 nm) exhibit excellent oxygen evolution reaction (OER) performance with an overpotential of 278 mV at 10 mA/cm2. The maximized number of active sites including oxygen vacancies, optimal adsorption strength, and the highest electrical conductivity are considered as the potential factors contributing to the excellent OER performance of Co-O NSs-2 nm. This work holds great significance for the precise thickness-tunable synthesis of transition metal layered hydroxide nanosheets with modulated and improved catalytic performance.

Homogeneous Metastable Hexagonal Phase Iridium Enhances Hydrogen Evolution Catalysis.

Catalytic reactions are surface-sensitive processes. Fabrication of homogeneous metastable metals can be used to promote phase-dependent catalytic performance; however, this has been a challenging task. Herein, homogeneous metastable hexagonal close-packed (hcp) Ir is epitaxially grown onto metastable phase hcp Ni, as demonstrated using spherical aberration electron microscopy. The as-fabricated metastable hcp Ir exhibits high intrinsic activity for the alkaline hydrogen evolution reaction (HER). In particular, metastable hcp Ir delivers a low overpotential of 17 mV at 10 mA cm-2 and presents a high specific activity of 8.55 mA cm-2 and a high turnover frequency of 38.26 s-1 at -0.07 V versus the reversible hydrogen electrode. Owing to its epitaxially grown structure, metastable hcp Ir is highly stable. Theoretical calculations reveal that metastable hcp Ir promotes H2 O adsorption and fast H2 O dissociation, which contributes to its remarkable HER activity. Findings can elucidate the crystal phase-controlled synthesis of advanced noble metal nanomaterials for the fundamental catalytic applications.

A One-Stone-Two-Birds Strategy to Functionalized Carbon Nanocages.

Carbon nanocages (CNCs) have attracted tremendous interest in heterogeneous catalysis due to their promising properties of porous structure and improved mass transfer. Nevertheless, the controlled synthesis of CNCs remains a great challenge. Herein, we have shown the successful construction of functionalized N-doped CNCs (NCNCs) via a one-stone-two-birds strategy. The selective use of hexacarbonyl molybdenum (Mo(CO)6) can not only protect the profile of the ZIF-8 precursor from collapse during thermal treatment but also be sacrificed for the functionalization of NCNCs after pyrolysis. Detailed mechanism studies reveal that Mo(CO)6 evolves into MoO3 on the surface of ZIF-8 and then facilitates the rapid pyrolysis of ZIF-8, leading to the formation of NCNCs decorated with small-sized MoC nanoparticles (MoC/NCNCs). The versatility of this one-stone-two-birds strategy has been validated by the generations of Cr- and W-decorated NCNCs. Moreover, MoC/NCNCs can serve as a selective and stable catalyst for furfural hydrogenation. This work provides a facile and universal strategy for fabricating and functionalizing CNCs, which attracts research interest in the fields of chemistry, material science, catalysis, and beyond.

Phase Engineering of a Ruthenium Nanostructure toward High-Performance Bifunctional Hydrogen Catalysis.

The physicochemical properties and catalytic performance of transition metals are highly phase-dependent. Ru-based nanomaterials are superior catalysts toward hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR), but studies are mostly limited to conventional hexagonal-close-packed (hcp) Ru, mainly arising from the difficulty in synthesizing Ru with pure face-centered-cubic (fcc) phase. Herein, we report a crystal-phase-dependent catalytic study of MoOx-modified Ru (MoOx-Ru fcc and MoOx-Ru hcp) for bifunctional HER and HOR. MoOx-Ru fcc is proven to outperform MoOx-Ru hcp in catalyzing both HER and HOR with much higher catalytic activity and more durable stability. The modification effect of MoOx gives rise to optimal adsorption of H and OH especially on fcc Ru, which thus has resulted in the superior catalytic performance. This work highlights the significance of phase engineering in constructing superior electrocatalysts and may stimulate more efforts on phase engineering of other metal-based materials for diversified applications.

A top-down strategy for amorphization of hydroxyl compounds for electrocatalytic oxygen evolution.

Amorphous materials have attracted increasing attention in diverse fields due to their unique properties, yet their controllable fabrications still remain great challenges. Here, we demonstrate a top-down strategy for the fabrications of amorphous oxides through the amorphization of hydroxides. The versatility of this strategy has been validated by the amorphizations of unitary, binary and ternary hydroxides. Detailed characterizations indicate that the amorphization process is realized by the variation of coordination environment during thermal treatment, where the M-OH octahedral structure in hydroxides evolves to M-O tetrahedral structure in amorphous oxides with the disappearance of the M-M coordination. The optimal amorphous oxide (FeCoSn(OH)6-300) exhibits superior oxygen evolution reaction (OER) activity in alkaline media, where the turnover frequency (TOF) value is 39.4 times higher than that of FeCoSn(OH)6. Moreover, the enhanced OER performance and the amorphization process are investigated with density functional theory (DFT) and molecule dynamics (MD) simulations. The reported top-down fabrication strategy for fabricating amorphous oxides, may further promote fundamental research into and practical applications of amorphous materials for catalysis.

Single-site Pt-doped RuO2 hollow nanospheres with interstitial C for high-performance acidic overall water splitting.

Realizing stable and efficient overall water splitting is highly desirable for sustainable and efficient hydrogen production yet challenging because of the rapid deactivation of electrocatalysts during the acidic oxygen evolution process. Here, we report that the single-site Pt-doped RuO2 hollow nanospheres (SS Pt-RuO2 HNSs) with interstitial C can serve as highly active and stable electrocatalysts for overall water splitting in 0.5 M H2SO4. The performance toward overall water splitting have surpassed most of the reported catalysts. Impressively, the SS Pt-RuO2 HNSs exhibit promising stability in polymer electrolyte membrane electrolyzer at 100 mA cm-2 during continuous operation for 100 hours. Detailed experiments reveal that the interstitial C can elongate Ru-O and Pt-O bonds, and the presence of SS Pt can readily vary the electronic properties of RuO2 and improve the OER activity by reducing the energy barriers and enhancing the dissociation energy of *O species.

Atomically Isolated Rh Sites within Highly Branched Rh2 Sb Nanostructures Enhance Bifunctional Hydrogen Electrocatalysis.

Breaking the bottleneck of hydrogen oxidation/evolution reactions (HOR/HER) in alkaline media is of tremendous importance for the development of anion exchange membrane fuel cells/water electrolyzers. Atomically dispersed active sites are known to exhibit excellent activity and selectivity toward diverse catalytic reactions. Here, a class of unique Rh2 Sb nanocrystals with multiple nanobranches (denoted as Rh2 Sb NBs) and atomically dispersed Rh sites are reported as promising electrocatalysts for alkaline HOR/HER. Rh2 Sb NBs/C exhibits superior HER performance with a low overpotential and a small Tafel slope, outperforming both Rh NBs/C and commercial Pt/C. Significantly, Rh2 Sb NBs show outstanding HOR performance of which the HOR specific activity and mass activity are about 9.9 and 10.1 times to those of Rh NBs/C, and about 4.2 and 3.7 times to those of Pt/C, respectively. Strikingly, Rh2 Sb NBs can also exhibit excellent CO tolerance during HOR, whose activity can be largely maintained even at 100 ppm CO impurity. Density functional theory calculations reveal that the unsaturated Rh sites on Rh2 Sb NBs surface are crucial for the enhanced alkaline HER and HOR activities. This work provides a unique catalyst design for efficient hydrogen electrocatalysis, which is critical for the development of alkaline fuel cells and beyond.

A Top-Down Strategy to Realize Surface Reconstruction of Small-Sized Platinum-Based Nanoparticles for Selective Hydrogenation.

Over the past decades, despite the substantial efforts that have been devoted to the modifications of Pt nanoparticles (NPs) to tailor their selectivities for hydrogenation reactions, there are still a lack of facile strategies for precisely regulation of the surface properties of NPs, especially for those with small sizes. In this work, we propose a top-down thermal annealing strategy for tuning the surface properties of Pt-based NPs (≈4 nm) without the occurrence of aggregation. Compared to conventional bottom-up methods, the present top-down strategy can precisely regulate the surface compositions of Pt-Cd NPs and other ternary Pt-Cd-M NPs (M=Fe, Ni, Co, Mn, and Sn). The optimized Pt-Cd NPs exhibit excellent selectivity toward phenylacetylene and 4-nitrostyrene hydrogenations with a styrene selectivity and 4-aminophenyl styrene selectivity of 95.2 % and 94.5 %, respectively. This work provides a general strategy for the surface reconstructions of Pt-based NPs, and promotes fundamental research on catalyst design for heterogeneous catalysis.