The performance of CO 2 methanation has critical relationships with oxygen vacancies, thus the fundamental insights of oxygen vacancies activation are of great importance. Herein, a series of Ni-based CeO 2 catalysts fabricated via impregnation and electrospinning methods were employed to study the variation of CO 2 methanation performance in terms of the dynamic analysis of intermediates and correlations of oxygen vacancies. The NiNPs@CeO 2 NF catalyst prepared by the co-electrospinning method shows superior catalytic performance with CO 2 conversion of 50.6 % and 82.3 % at the low temperature of 250 °C and 300 °C, respectively, as well as excellent stability of 60 h at a high temperature of 400 °C. The achieved catalytic properties could be attributed to the confined environment and synergistic effect between Ni nanoparticles and CeO 2 nanofibers. Additionally, in-situ Raman verified that nanofibers can form more active oxygen vacancies and adsorb well with CO 2 . In-situ DRIFTS analysis reveals that the monodentate and bridging bidentate formate were the key intermediates for CO 2 methanation. • NiNPs@CeO 2 NF catalyst prepared by a novel electrospinning method for CO 2 methanation. • NiNPs@CeO 2 NF catalyst performs excellent activity due to the synergistic effect between NiNPs and nanofibers. • The dynamic progress of oxygen defects was recorded by in-situ Raman. • The key intermediate of formate for CO 2 methanation was revealed by in-situ DRIFTS. 

Ni nanoparticles enclosed in highly mesoporous nanofibers with oxygen vacancies for efficient CO2 methanation

The development of novel cost-efficient, high-performing catalysts for CO2 methanation that are active at low temperatures can be optimized through the understanding of the reaction mechanism on different materials. A series of Ni-based catalysts supported on CeO2 and carbon/CeO2 composites was investigated, showing that Ni nanoparticles supported on a carbon/CeO2 composite with a 50:50 wt ratio and on pure CeO2 have excellent low-temperature activity and achieve up to 87% CO2 conversion with full selectivity towards CH4 at 370 °C. Importantly, meaningful insights on the reaction mechanism were gathered for the different types of materials by using the emerging ME−PSD−DRIFTS technique. The study of the rate of formation/consumption of the various intermediates showed that the CO2 methanation reaction follows a combination of the CO and formate pathways in the case of Ni on pure CeO2; however, in the case of Ni on the carbon/CeO2 composite, it follows only the formate pathway. 

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In situ investigation of the CO2 methanation on carbon/ceria-supported Ni catalysts using modulation-excitation DRIFTS

Nickel phyllosilicates functionalized with graphene oxide to boost CO selectivity in CO2 hydrogenation

• A flexible glucose sensor is fabricated based on multilayer laser-induced graphene. • The sensor exhibits wide linear range and high sensitivity towards glucose. • No signal attenuation is observed after drastic folding for 100 times. • The sensor has been applied to the determination of glucose in human serum. Wearable biosensors that can detect glucose molecules is a promising monitoring device for clinic and health-care analysis. A flexible enzyme-free glucose sensor based on multilayer porous laser-induced graphene (LIG) produced from polyimide (PI) film was developed in this work. Ni/LIG electrode was prepared by electrochemical deposition of Ni nanoparticles on LIG for enzyme-free glucose detection. Ag/AgCl/LIG was prepared as the reference by coating with silver conductive gel and electrochemical anodization methods on LIG. The Ni/LIG glucose sensor possesses excellent flexibility and can function properly after being folded for a hundred times. The sensor exhibits desirable analytical performance towards glucose with wide linear range (0.50 μM to 1666 μM), ultra-high sensitivity (2040 μA/mM·cm 2 ), and low detection limit (0.29 μM). Ni/LIG glucose sensor also shows high stability and minimal responses to the interference substances and has been successfully applied to the determination of glucose in human blood serum with a relative standard deviation (RSD, n = 10) of 0.85%, and recoveries ranging from 99.36% to 100.45%. 

A wearable enzyme-free glucose sensor based on nickel nanoparticles decorated laser-induced graphene

Effect of Ni ratio on mesoporous Ni/MgO nanocatalyst synthesized by one-step hydrothermal method for thermal catalytic decomposition of CH4 to H2

Graphene Aerogel Supported Ni for CO2 Hydrogenation to Methane

Engineering morphologies of yttrium oxide supported nickel catalysts for hydrogen production

As a pure combustible gas with a high calorific value, methane has long been favored, and that is why the CO2 methanation reaction is attracting more and more attention. However, it is still challenging for this reaction due to the chemical inertness of CO2 molecules, poor reaction efficiency at low temperatures, catalyst sintering at high temperatures, and carbon monoxide toxicity. Herein, the ammonia evaporation method was utilized to synthesize a series of Zn-modified Ni/SiO2 catalysts with high surface area and high dispersity of active metals. The 80Ni-Zn/SiO2 catalyst with an appropriate Ni/Zn molar ratio of 80:1 exhibited a high-performance breakthrough with a CO2 conversion greater than 80% at 300 °C, good stability for 40 h at 310 °C, and a gas hourly space velocity of 18,000 mL·g–1·h–1. These catalysts were further characterized by using a series of methods like in situ diffuse reflectance infrared Fourier transform spectroscopy to investigate the structural properties and potential reaction pathways. The effect of the Zn promoter on the Ni/SiO2 catalyst for CO2 methanation has been well investigated, namely, improving Ni dispersion and enhancing the H2 adsorption. The findings demonstrate the broad availability, affordability, and remarkable high-performance practicability of the raw ingredients for the production of Ni-based catalysts for commercial applications. 

Xiaohan Chen

Papers

Graphene Aerogel Supported Ni for CO2 Hydrogenation to Methane

Ni nanoparticles enclosed in highly mesoporous nanofibers with oxygen vacancies for efficient CO2 methanation

Engineering morphologies of yttrium oxide supported nickel catalysts for hydrogen production

Insights into the Zn Promoter for Improvement of Ni/SiO2 Catalysts Prepared by the Ammonia Evaporation Method toward CO2 Methanation

Effect of Y2o3 Morphologies on the Catalytic Performance of Ni/Y2o3 Catalysts for Ammonia Decomposition