High-loading, ultrafine Ni nanoparticles dispersed on porous hollow carbon nanospheres for fast (de)hydrogenation kinetics of MgH_(2)

Magnesium hydride(MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign;however, it suffers from high dehydrogenation temperature and slow sorption kinetics.Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles(NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2are lowered to 190 and 242 ℃, respectively. 6.2 wt% H2is rapidly released within 30 min at 250 ℃. The amount of H2that the dehydrogenation product can absorb at a low temperature of 150 ℃ in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active,reacting with MgH2and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the(de)hydrogenation kinetics of MgH2.

Bioresource Upgrade for Sustainable Energy,Environment,and Biomedicine

We conceptualize bioresource upgrade for sustainable energy,environment,and biomedicine with a focus on circular economy,sustainability,and carbon neutrality using high availability and low utilization biomass(HALUB).We acme energy-efficient technologies for sustainable energy and material recovery and applications.The technologies of thermochemical conversion(TC),biochemical conversion(BC),electrochemical conversion(EC),and photochemical conversion(PTC)are summarized for HALUB.Microalgal biomass could contribute to a biofuel HHV of 35.72 MJ Kg^(-1)and total benefit of 749$/ton biomass via TC.Specific surface area of biochar reached 3000 m^(2)g^(-1)via pyrolytic carbonization of waste bean dregs.Lignocellulosic biomass can be effectively converted into bio-stimulants and biofertilizers via BC with a high conversion efficiency of more than 90%.Besides,lignocellulosic biomass can contribute to a current density of 672 mA m^(-2)via EC.Bioresource can be 100%selectively synthesized via electrocatalysis through EC and PTC.Machine learning,techno-economic analysis,and life cycle analysis are essential to various upgrading approaches of HALUB.Sustainable biomaterials,sustainable living materials and technologies for biomedical and multifunctional applications like nano-catalysis,microfluidic and micro/nanomotors beyond are also highlighted.New techniques and systems for the complete conversion and utilization of HALUB for new energy and materials are further discussed.

Factors Affecting the Catalytic Performance of Nano-catalysts

Comprehensive Summary Nano-catalysis plays a vital role in the industrially chemical transformations.The increasingly severe energy crisis and environmental issues spur scientists to exploit novel nano-catalysts in diverse fields.It is essential to understand the fundamental physicochemical properties of nano-catalysts to develop efficient systems,whose design can be subsequently precisely tuned at the atomic level.In this review,we summarize several key factors affecting the catalytic activity of nano-catalysts,including structure,composition,size,and interface,providing guidance for the atomic level control of high-efficient nano-catalysts.Finally,we present a brief conclusion and some thoughts on nano-catalysis.