Qi Shao

Highly Active and Selective Hydrogenation of CO2 to Ethanol by Ordered Pd–Cu Nanoparticles

Carbon dioxide (CO2) hydrogenation to ethanol (C2H5OH) is considered a promising way for CO2 conversion and utilization, whereas desirable conversion efficiency remains a challenge. Herein, highly active, selective and stable CO2 hydrogenation to C2H5OH was enabled by highly ordered Pd-Cu nanoparticles (NPs). By tuning the composition of the Pd-Cu NPs and catalyst supports, the efficiency of CO2 hydrogenation to C2H5OH was well optimized with Pd2Cu NPs/P25 exhibiting high selectivity to C2H5OH of up to 92.0% and the highest turnover frequency of 359.0 h-1. Diffuse reflectance infrared Fourier transform spectroscopy results revealed the high C2H5OH production and selectivity of Pd2Cu NPs/P25 can be ascribed to boosting *CO (adsorption CO) hydrogenation to *HCO, the rate-determining step for the CO2 hydrogenation to C2H5OH.

PtPb/PtNi Intermetallic Core/Atomic Layer Shell Octahedra for Efficient Oxygen Reduction Electrocatalysis

Although explosive studies on pursuing high-performance Pt-based nanomaterials for fuel cell reactions have been carried out, the combined controls of surface composition, exposed facet, and interior structure of the catalyst remains a formidable challenge. We demonstrate herein a facile chemical approach to realize a new class of intermetallic Pt-Pb-Ni octahedra for the first time. Those nanostructures with unique intermetallic core, active surface composition, and the exposed facet enhance oxygen reduction electrocatalysis with the optimized PtPb1.12Ni0.14 octahedra exhibiting superior specific and mass activities (5.16 mA/cm2 and 1.92 A/mgPt) for oxygen reduction reaction (ORR) that are ∼20 and ∼11 times higher than the commercial Pt/C, respectively. Moreover, the PtPb1.12Ni0.14 octahedra can endure at least 15 000 cycles with negligible activity decay, showing a new class of Pt-based electrocatalysts with enhanced performance for fuel cells and beyond.

Nanoscale Trimetallic Metal-Organic Frameworks Enable Efficient Oxygen Evolution Electrocatalysis

Metal-organic frameworks (MOFs) are a class of promising materials for diverse heterogeneous catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports focus on using MOFs as templates to in situ create efficient electrocatalysts through annealing. Herein, we prepared a series of Fe/Ni-based trimetallic MOFs (Fe/Ni/Co(Mn)-MIL-53 accordingly to the Material of Institute Lavoisier) by solvothermal synthesis, which can be directly adopted as highly efficient electrocatalysts. The Fe/Ni/Co(Mn)-MIL-53 shows a volcano-type oxygen evolution reaction (OER) activity as a function of compositions. The optimized Fe/Ni2.4 /Co0.4 -MIL-53 can reach a current density of 20 mA cm-2 at low overpotential of 236 mV with a small Tafel slope of 52.2 mV dec-1 . In addition, the OER performance of these MOFs can be further enhanced by directly being grown on nickel foam (NF).

A Cost-Efficient Bifunctional Ultrathin Nanosheets Array for Electrochemical Overall Water Splitting

The design of cost-efficient earth-abundant catalysts with superior performance for the electrochemical water splitting is highly desirable. Herein, a general strategy for fabricating superior bifunctional water splitting electrodes is reported, where cost-efficient earth-abundant ultrathin Ni-based nanosheets arrays are directly grown on nickel foam (NF). The newly created Ni-based nanosheets@NF exhibit unique features of ultrathin building block, 3D hierarchical structure, and alloy effect with the optimized Ni5 Fe layered double hydroxide@NF (Ni5 Fe LDH@NF) exhibiting low overpotentials of 210 and 133 mV toward both oxygen evolution reaction and hydrogen evolution reaction at 10 mA cm-2 in alkaline condition, respectively. More significantly, when applying as the bifunctional overall water splitting electrocatalyst, the Ni5 Fe LDH@NF shows an appealing potential of 1.59 V at 10 mA cm-2 and also superior durability at the very high current density of 50 mA cm-2 .

A general approach to synthesise ultrathin NiM (M = Fe, Co, Mn) hydroxide nanosheets as high-performance low-cost electrocatalysts for overall water splitting

Electrochemically splitting water into hydrogen (H2) and oxygen (O2) is a promising method for clean energy generation, while the absence of highly active, stable, low-cost and earth abundant catalysts greatly impedes its large-scale application. Herein, we report a general and robust approach for the controlled synthesis of a class of NiM (M = Fe, Co, Mn) hydroxide nanosheets (HNSs) that have ultrathin thicknesses of around 2 nm. Such unique structures enable the HNSs to have promising oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances, with the NiFe HNSs being the best candidate. Given the well-defined electrochemical bifunctionality, a full alkaline electrolyzer was constructed using NiFe HNSs as both the cathodic and the anodic catalysts. It can realize overall water splitting with a current density of 10 mA cm−2 at 1.67 V and has remarkable durability for 12 h. This work opens a new avenue to approach water splitting catalysis using efficient low-cost Ni-based HNSs.

Highly Efficient Carbon Dioxide Hydrogenation to Methanol Catalyzed by Zigzag Platinum–Cobalt Nanowires

Carbon dioxide (CO2 ) hydrogenation is an effective strategy for CO2 utilization, while unsatisfied conversion efficiencies remain great challenges. It is reported herein that zigzag Pt-Co nanowires (NWs) with Pt-rich surfaces and abundant steps/edges can perform as highly active and stable CO2 hydrogenation catalysts. It is found that tuning the Pt/Co ratio of the Pt-Co NWs, solvents, and catalyst supports could well optimize the CO2 hydrogenation to methanol (CH3 OH) with the Pt4 Co NWs/C exhibiting the best performance, outperforming all the previous catalysts. They are also very durable with limited activity decays after six catalytic cycles. The diffuse reflectance infrared Fourier transform spectroscopy result of CO2 adsorption shows that the Pt4 Co NWs/C undergoes the adsorption/activation of CO2 by forming appropriate carboxylate intermediates, and thus enhancing the CH3 OH production.

Multicomponent Pt-Based Zigzag Nanowires as Selectivity Controllers for Selective Hydrogenation Reactions

The selective hydrogenation of α, β-unsaturated aldehyde is an extremely important transformation, while developing efficient catalysts with desirable selectivity to highly value-added products is challenging, mainly due to the coexistence of two conjugated unsaturated functional groups. Herein, we report that a series of Pt-based zigzag nanowires (ZNWs) can be adopted as selectivity controllers for α, β-unsaturated aldehyde hydrogenation, where the excellent unsaturated alcohol (UOL) selectivity (>95%) and high saturated aldehyde (SA) selectivity (>94%) are achieved on PtFe ZNWs and PtFeNi ZNWs+AlCl3, respectively. The excellent UOL selectivity of PtFe ZNWs is attributed to the lower electron density of the surface Pt atoms, while the high SA selectivity of PtFeNi ZNWs+AlCl3 is due to synergy between PtFeNi ZNWs and AlCl3, highlighting the importance of Pt-based NWs with precisely controlled surface and composition for catalysis and beyond.

Ultrathin Vein-Like Iridium–Tin Nanowires with Abundant Oxidized Tin as High-Performance Ethanol Oxidation Electrocatalysts

Iridium (Ir) holds great promise for ethanol oxidation reaction (EOR), while its practical applications suffer from the limited shape-controlled synthesis due to its low-energy barrier for nucleation. To overcome this limitation, the preparation of a new class of ultrathin vein-like Ir-tin nanowires (IrSn NWs) with abundant oxidized Sn is reported. By tuning the ratio of Ir to Sn, the optimized Ir67 Sn33 /C exhibits the highest mass density of 95.6 mA mg-1 Ir for EOR at low potential (0.04 V), which is 4.1-fold and 20-fold higher than that of Ir/C and the commercial Pt/C, respectively. It also exhibits the smallest Tafel slope of 153 mV dec-1 and superior stability after 2 h chronoamperometric measurement. Electrochemical measurements and X-ray photoelectron spectra results confirm that the abundant oxidized Sn promotes a complete oxidization of ethanol into CO2 at low potential. This work highlights the importance of non-noble metal on enhancing the EOR performance.

Networked Pt–Sn nanowires as efficient catalysts for alcohol electrooxidation

Direct alcohol fuel cells (DAFCs) have attracted growing research interest as clean high-efficiency energy conversion devices, however the design and creation of high-performance anode catalysts for DAFCs is still extremely desirable. Herein, we report a wet-chemical method for making bimetallic aerogel networked Pt–Sn nanowires (NWs) with tunable compositions. All of the obtained networked Pt–Sn NWs exhibit better mass activities and specific activities in both the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) than commercial Pt/C due to their unique three-dimensional (3D) porosity with larger surface areas and the presence of structural defects, with the optimized networked Pt6Sn3 NWs displaying the best mass activities of up to 1.08 mA μgPt−1 for the EOR and 1.45 mA μgPt−1 for the MOR in acid media. The networked Pt6Sn3 NWs also exhibited enhanced stability toward both the EOR and MOR compared to Pt/C. The present work suggests that the networked NWs with high surface areas and rich defects are indeed a unique class of efficient electrocatalysts for alcohol electrooxidation.

Promoting the Direct H2O2 Generation Catalysis by Using Hollow Pd–Sn Intermetallic Nanoparticles

Although direct hydrogen (H2 ) oxidation to hydrogen peroxide (H2 O2 ) is considered as a promising strategy for direct H2 O2 synthesis, the desirable conversion efficiency remains formidable challenge. Herein, highly active and selective direct H2 oxidation to H2 O2 is achieved by using hollow Pd-Sn intermetallic nanoparticles (NPs) as the catalysts. By tuning the catalytic solvents and catalyst supports, the efficiency of direct H2 oxidation to H2 O2 can be optimized well with the hollow Pd2 Sn NPs/P25 exhibiting H2 O2 selectivity up to 80.7% and productivity of 60.8 mol kgcat-1 h-1 . In situ diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption results confirm the different surface atom arrangements between solid and hollow Pd-Sn NPs. X-ray photoelectron spectra results show that the higher efficiency of Pd2 Sn NPs/P25 is due to its higher content of metallic Pd and higher ratio of Snx+ , which benefit H2 O2 production and selectivity.