Highly ordered aluminum-containing mesoporous silica (Al-MCM-41) was prepared using attapulgite clay mineral as a Si and Al source. Mesoporous complexes embedded with CuO nanoparticles were subsequently prepared using various copper sources and different copper loadings in a direct synthetic route. The resulting CuO/Al-MCM-41 composite possessed p6mm hexagonally symmetry, well-developed mesoporosity, and relatively high BET surface area. In comparison to pure silica, these mesoporous materials embedded with CuO nanoparticles exhibited smaller pore diameter, thicker pore wall, and enhanced thermal stability. Long-range order in the aforementioned samples was observed for copper weight percentages as high as 30%. Furthermore, a significant blue shift of the absorption edge for the samples was observed when compared with that of bulk CuO. H2-TPR measurements showed that the direct-synthesized CuO/Al-MCM-41 exhibited remarkable redox properties compared to the post-synthesized samples, and most of the CuO nanoparticles were encapsulated within the mesoporous structures. The possible interaction between CuO and Al-MCM-41 was also investigated.

Pristine halloysite nanotubes (HNTs) were pretreated to produce mesoporous silica nanotubes (MSiNTs), which was further impregnated with polyethenimine (PEI) to prepare an emerging nanocomposite MSiNTs/PEI (MP) for CO2 capture. Thermogravimetric analysis (TGA) was employed to analyze the influences of PEI loading amount and adsorption temperature on CO2 adsorption capacity of the nanocomposite. The Brunauer-Emmett-Teller (BET) surface area (SBET) of MSiNTs was six times higher than that of HNTs, and the corresponding pore volume was more than two times higher than that of HNTs. The well dispersion of PEI within the nanotubes of MSiNTs benefits more CO2 gas adsorption, and the adsorption capacity of the nanocomposite could reach 2.75 mmol/g at 85 °C for 2 h. The CO2 adsorption on the nanocomposite was demonstrated to occur via a two-stage process: initially, a sharp linear weight increase at the beginning, and then a relatively slow adsorption step. The adsorption capacity could reach as high as 70% within 2 min. Also, the nanocomposite exhibited good stability on CO2 adsorption/desorption performance, indicating that the as-prepared emerging nanocomposite show an interesting application potential in the field of CO2 capture.

No abstract

No abstract

consumption leads to a range of environmental problems such as air pollution, thermal pollution, global warming, and resource shortage. [1,2] Therefore, the development of clean, renewable, and new energy that can replace traditional fossil fuels is the top priority of energy development. [3] Hydrogen energy is the most promising clean energy, with high combustion calorific value (4.5 times coke). [4] Hydrogen produces water when converting chemical energy, contributing to recycling resources. [5] There are three kinds of techniques for hydrogen production: photocatalysis, water electrolysis, and biomass reforming. Global generate electricity by using renewable energy such as wind, water, and solar energy, but the storage problem of electricity leads to incomplete utilization of electricity. [6][7][8] Water electrolysis only needs renewable electric power to drive the reaction, and it has attracted wide attention due to pollution-free and low cost. [9] As a result, water electrolysis has very broad prospects in solving energy and environmental problems.Water electrolysis technology gets hydrogen by converting electrical energy into chemical energy, oxygen is obtained on the anode via the oxygen evolution reaction (OER), and hydrogen is obtained on the cathode via the hydrogen evolution reaction (HER). [10] As commercial electrocatalysts on the anode side of electrolyzer, Ir-based catalysts can not only survive under high corrosion conditions but also show efficient catalytic performance. Noble metal materials (Ir-based OER catalysts and Pt-based HER catalysts) are the best catalysts, but the high price and rare reserves limit their long-term commercial applications. [11,12] Therefore, catalysts with high activity and low cost are the ongoing research targets. The exposure of OER catalysts to highly corrosive and oxidative conditions cause severe inactivation and instability, which is one of bottlenecks for largescale application of water electrolysis. The most stable catalyst is the corroded Fe foam, which maintains a current density of 1000 mA cm −2 at 5000 h. [13] Co 3 O 4 @CoO can maintain a steady current of >1000 h without showing significant decay. [14] However, the short-term stability of some catalysts does not meet the requirements of practical applications.This review presents the recent progress of OER and HER catalysts. Through a summary of the reaction mechanisms of OER and HER, it is clear about the specific steps in the occurrence of OER and HER. The rate-determining steps of OER and HER can indicate a specific direction for the design of the catalysts. And then focus on the recent progress on surface design of various OER and HER catalysts and find that the catalyst surface regulation plays an important role in the catalyst design.Hydrogen, a new energy carrier that can replace traditional fossil fuels, is seen as one of the most promising clean energy sources. The use of renewable electricity to drive hydrogen production has very broad prospects for addressing energy and environmental problems. T...