Research Progress----Shanghai Advanced Research Institute,Chinese Academy of Sciences

Novel Approach to 3D Printed Nickel-based Electrocatalysts for Highly-efficient Hydrogen Evolution

A research team at Shanghai Advanced Research Institute reported a novel photo-curing 3D-printing method to manufacture directly the structured nickel-based electrocatalysts with unique gluten-like cubic structure and strong catalyst-substrate interaction.The research results were published in Nano Energy.

Water electrolysis has proved to be an effective method of producing hydrogen employing renewable sources of energy, contributing the national commitment to carbon peak and carbon neutrality.The development of cost-effective electrocatalysts for efficient and durable hydrogen evolution reaction (HER) in alkaline media is of vital importance to meet the increasing demand of hydrogen. The platinum group metals (PGMs) exhibit excellent activity towards the HER, but their high cost hinders their widespread application.Motivated by such a challenge, a research team led by Prof. TANG Zhiyong and Associate Prof. ZHANG Jie at Shanghai Advanced Research Institute reported a novel photo-curing 3D-printing method to manufacture directly the structured nickel-based electrocatalysts with unique gluten-like cubic structure and strong catalyst-substrate interaction.The research results were published in Nano Energy.The photo-curing 3D printing has much lower manufacturing cost than the selective laser melting (SLM) 3D printing, and much higher degree of freedom and printing accuracy than that of direct ink writing (DIW) 3D printing.Based on this technology, researchers optimized printing paste composition and post-treatment process. The resultant electrode surface exhibits gluten-like cubic structure, where Ti exists in amorphous state with strong interaction with Ni, leading to increased active sites and greatly improved electrolytic properties.The tailored Ti-Ni NS electrode exhibits excellent durability and a remarkable low overpotential, surpassing the commercial Pt/C catalyst and most of the state-of-the-art electrocatalysts.Density functional theory (DFT) calculations further reveal that the Ti doping significantly decreases the energy barrier of water dissociation and hydrogen energy barrier, thus enhancing the HER.This work provides a novel strategy to precisely prepare the structured noble-metal-free catalysts with enhanced activity in alkaline water electrolysis(AWE). Moreover, the developed photo-curable 3D printing method provides an alternative option for manufacturing low-cost electrocatalysts with complex 3D architecture.
　　Schematic illustration of photo-curing 3D printing of Ni-based electrode (Image by SARI)
　　

2022-08-12 more+

A Novel Approach for Generating Coherent and Ultrashort Soft X-ray Pulses

A research team from Shanghai Advanced Research Institute reported on the first demonstration of an external seeding mechanism, termed echo-enabled harmonic cascade (EEHC) for generating coherent and ultrashort soft x-ray pulses.

Generation of intense, tunable, and fully coherent pulses in the X-ray regime has been a long-standing challenge for laser technologies. The urgent need for intense X-ray light sources has prompted the development of X-ray free-electron lasers (FELs). However, most of the presently existing X-ray FEL facilities are faced with limited temporal coherence and large shot-to-shot fluctuations.
　　An efficient way to generate ‘laser-like’ FEL is to employ an external laser source as the ‘seed’ to dominate the gain process and control the output properties. Current limitations on seeded FELs are the low harmonic up-conversion efficiency (limits the short wavelength coverage) and long output pulse duration (determined by the length of the external laser).
　　To overcome the above-mentioned limitations of seeded FELs, a research team from Shanghai Advanced Research Institute reported on the first demonstration of an external seeding mechanism, termed echo-enabled harmonic cascade (EEHC) for generating coherent and ultrashort soft x-ray pulses.
　　The results were published in Optica.
　　The EEHC mechanism uses echo-enabled harmonic generation as the first stage, producing intense extreme ultraviolet pulses that seed the second stage x-ray free-electron laser (FEL) with the high-gain harmonic generation setup. The mechanism shows that 100 MW-level peak power, transform-limited soft X-ray pulses with tunable pulse duration from 25 fs to 55 fs can be generated. Comparing with previous demonstrated seeded FEL mechanisms, EEHC holds the superiorities of much higher harmonic up-conversion efficiency and tunable pulse durations.
　　Besides the temporal coherence, researchers have also demonstrated a unique feature of EEHC on generating isolated ultrashort pulses. The supreme up-frequency conversion efficiency and flexible pulse length control of this EEHC mechanism allows to exceed the current limitations of seeded FELs while preserving the coherence of the seed.
　　These features of EEHC are a step towards fully coherent and ultrashort x-ray lasers and could unlock the door for extending nonlinear optical techniques to the sub-nanometer wavelength and few-femtosecond time duration range.
　　Fig. 1 FEL gain curves for the first- (left) and second-stages (Image by SARI)
　　

2022-08-08 more+

Researchers Develop Novel Au Catalyst for Hydroformylation

A research team from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences designed a zeolite-encaged Au single-atom catalyst with Au1-O-SiOX motifs, which shows remarkable catalytic activity and selectivity towards propene hydroformylation.

　　As one of the largest-volume industrial chemical processes today, hydroformylation converts olefins, H2 and CO into aldehydes and related products more than 10 million tons annually.
　　Although Au exhibits good ability towards olefins activation, H2 dissociation and CO bonding, it is conventionally considered inactive for hydroformylation due to its intrinsic inertness.
　　Now, a research team led by Profs. WANG Hui and SUN Yuhan from the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences designed a zeolite-encaged Au single-atom catalyst with Au1-O-SiOX motifs, which shows remarkable catalytic activity and selectivity towards propene hydroformylation.
　　The study was published in Chem Catalysis on July 13.
　　Preliminary performance evaluation of impregnated Au on zeolite demonstrates that sub-nanometer Au clusters exhibit higher activity than nanoparticles in hydroformylation. Inspired by this, the confinement effect of zeolite is utilized to regulate the particle size of Au. Nanoparticles/sub-nanoclusters and atomically dispersed Au species within zeolite can be unambiguously observed through high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM).
　　The Au1@S-1 catalyst shows a total 3,794 μmol butyraldehyde and noticeable stability after 5 cycles, which is about one order of magnitude more active than Au nanoparticles and is even comparable to Rh-based catalysts.
　　Detailed characterizations and theoretical calculations indicate that the isolated Au atoms within the zeolite matrix are stabilized via oxygen bridge bonds. The formed Au1-O-SiOX motifs render maximum active site density and high structural stability, which are identified as the real active sites for efficient hydroformylation.
　　This work makes conventionally inactive Au efficient alternative for hydroformylation by reasonably tailoring the size, contact structure and electronic environment of active metals on specific reactions.
　　Structural modeling and performance comparison of Au-based catalysts (Image by SARI)
　　

2022-07-14 more+

Scientists Reveal Gas Nanobubbles Accelerate Solid-liquid-gas Reaction

A research group reported a real-time observation of the accelerated solid-liquid-gas etching progress of gold nanorods by introducing gas nanobubbles and revealed the underlying microscopic mechanism dependent on liquid layer thickness.

Solid–liquid–gas reactions are encountered in various natural phenomenon and industrial applications, such as hydrogen–oxygen fuel cell reactions, heterogeneous catalysis, metal corrosion in ambient environments, etc.
　　However, due to the absence of quantitative analysis of the reaction dynamics and an understanding of gas transport mechanism at the solid–liquid–gas interface, a comprehensive understanding of gas transport in liquid and following reactions at the triple-phase interfaces remains unclear.
　　Motivated by this challenge, Prof. CHEN Jige at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with Prof. FANG Haiping at East China University of Science and Technology, Prof. Sun Litao at Southeast University, and Prof. ZHENG Haimei at Lawrence Berkeley National Laboratory, reported a real-time observation of the accelerated solid-liquid-gas etching progress of gold nanorods by introducing gas nanobubbles and revealed the underlying microscopic mechanism dependent on liquid layer thickness. The results were published in the latest Nature Materials.
　　In this work, the real-time observation of the accelerated etching of gold nanorods with oxygen nanobubbles in aqueous hydrobromic acid is given by using liquid-cell transmission electron microscopy (TEM). It is found that when an oxygen nanobubble is close to a nanorod below the critical distance (~1 nm), the local etching rate is significantly enhanced by over one order of magnitude. Molecular dynamics simulation results reveal that the strong attractive van der Waals interaction between the gold nanorod and oxygen molecules governs oxygen transport through the thin liquid layer and thus leads to enhanced etching rate.
　　The finding of a critical distance for etching acceleration between nanobubbles and gold nanorods leads to dramatical different physics picture, which is different from the conventional view that a more rapid reaction of nanobubbles toward the solid relates to a more rapid reaction. This study sheds light on the rational design of solid–liquid–gas reactions for enhanced activities and provides a promising approach to modify the solid–liquid–gas reaction rate. Moreover, it shows that liquid-cell TEM provides an observational and mechanistic understanding of the triple-phase reaction at relevant temporal and distance scales, which offers great potential for addressing many fundamental issues where nanoscale gas and liquid states are involved.Accelerated gold nanorods etching by introducing oxygen nanobubbles (Image by SARI)

2022-07-11 more+

Novel Silver Hollow Fiber Boosts CO2 Electroreduction

A research team led by Prof. WEI Wei and CHEN Wei reported a hierarchical micro/nanostructured silver hollow fiber electrode that reduces CO2 to CO with CO2 conversions exceeding 54% at a high space velocity of 31000 mL？gcat-1？h-1 under ambient conditions, maintaining stable large current densities (~1.26 A？cm-2) and high CO faradaic efficiencies (~93%). The results were published in the latest Nature Communications.

　　The electrochemical conversion of CO2 into carbon-based fuels and valuable feedstocks by renewable electricity is an attractive strategy for addressing CO2 abatement and renewable energy consumption, which is of great significance for achieving the goal of carbon neutralization.
　　CO is the important component of syngas (a mixture of CO and H2), which can be directly converted into various value-added chemicals via well-developed industrial processes such as Fischer-Tropsch synthesis, methanol synthesis, etc. Therefore, CO2 electroreduction to CO is considered one of the most promising routes to obtain cost-competitive products. However, highly efficient CO2 conversion with high space velocity under mild conditions remains a challenge.
　　Motivated by such challenge, a research team led by Prof. WEI Wei and CHEN Wei reported a hierarchical micro/nanostructured silver hollow fiber electrode that reduces CO2 to CO with CO2 conversions exceeding 54% at a high space velocity of 31,000 mL · gcat-1 · h-1 under ambient conditions, maintaining stable large current densities (~1.26 A·cm-2) and high CO faradaic efficiencies (~93%). The results were published in the latest Nature Communications.
　　The reported hollow fiber electrode with hierarchical micro/nanostructures composed of only metallic silver (Ag) for electroreducing CO2 to CO. Such a porous hollow-fiber Ag electrode acting as a CO2 disperser not only enhances three-phase interface reactions but also guides mass transfers during electrolysis. Electrochemical results and time-resolved operando Raman spectra demonstrate that enhanced three-phase interface reactions and oriented mass transfers synergistically boost CO production.
　　This result provides new opportunities for heightening three-phase interface reactions and mass transfer kinetics simultaneously. In addition, it demonstrates that activated Ag HF can be an ideal industrial electrode with excellent durability, representing an encouraging headway in CO2 electroreduction that may lead to scalable applications.
　　Schematic illustration of hollow fiber electrode for boosting CO2 reduction to CO (Image by SARI)
　　

2022-06-02 more+

Tandem Catalysis Improve Selective Oxidation of Methane to Oxygenates

a research team led by Prof. SUN Yuhan and Prof. ZHONG Liangshu at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a ZSM-5 (Z-5) supported PdCu catalyst for selective oxidation of CH4 to oxygenates using O2 in the presence of H2. The as-obtained PdCu/Z-5 catalyst exhibited a high oxygenates yield of 1178 mmol/gPd/h with oxygenates selectivity of 95% at 120 °C. The research results were published in the latest issue of Angew. Chem. Int. Ed.

　　Direct conversion of methane to oxygenates has attracted numerous research interests from both industrial and academics. However, selective oxidation of methane to value-added chemicals with both high catalytic activity and selectivity under mild conditions still remains a great challenge.
　　Firstly, selective oxidation of CH4 to oxygenates with O2 or O2/H2 suffers from low catalytic activity and low oxygenates selectivity, due to the low activity of oxygen and the overoxidation of the oxygenates. Secondly, the high loading (1~5 wt%) of noble metals for supported catalysts used for methane conversion leads to high cost, which is not business-friendly.
　　Inspired by these challenges, a research team led by Prof. SUN Yuhan and Prof. ZHONG Liangshu at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences reported a ZSM-5 (Z-5) supported PdCu catalyst for selective oxidation of CH4 to oxygenates using O2 in the presence of H2. The as-obtained PdCu/Z-5 catalyst exhibited a high oxygenates yield of 1178 mmol/gPd/h with oxygenates selectivity of 95% at 120 °C. The research results were published in the latest issue of Angew. Chem. Int. Ed.
　　Based on a combination of control experiments and electron paramagnetic resonance as well as in situ spectroscopic techniques, researchers found that PdO nanoparticles facilitated in situ generation of H2O2, while Cu single atoms not only accelerated the generation of abundant ·OH from H2O2 decomposition, but also enabled the homolytic cleavage of CH4 by ·OH to ·CH3. Subsequently, the ·OH reacted quickly with the ·CH3 to form CH3OH with high selectivity.
　　These findings may provide valuable insights into selective oxidation of methane to oxygenates, which may also shed light on other highly efficient and low-price catalysts for the selective activation of C-H bonds in light alkanes.
　　Product yield and oxygenates selectivity for selective oxidation of CH4 with O2 and H2. (Image by SARI)
　　

2022-04-14 more+