Electricity Harvesting from Water Evaporation on Hierarchical Pore Gradient Silica Aerogel-Based Generators.

In this study, the electric energy harvesting capability of the hierarchical pore gradient silica aerogel (HPSA) is demonstrated due to its unique porous structure and inherent hydroxyl groups on the surface. Taking advantage of the positively charged surface of unwashed HPSA credited by the preparation strategy, poly(4-styrene sulfonic acid) (PSS) can be spontaneously adsorbed onto unwashed HPSA and shows gradient distribution due to the pore-gradient structure of HPSA. By virtue of the gradient distribution and the stronger ionization of PSS, PSS-modified HPSA (PSS-HPSA) shows enhanced electricity generation performance from natural water evaporation with an average output voltage of 0.77 V on an individual device. The water evaporation-induced electricity property of PSS-HPSA can be maintained in the presence of a low concentration of salt. The desirable salt resistance capability benefits from the unique 3D hierarchical porous structure of HPSA which ensures rapid water replenishment so as to effectively avoid the salt accumulation. The HPSA-based devices with the advantages of unique porous structure, easy functionalization, good physicochemical stability, good salt resistance capability, and eco-friendliness show great potential as water evaporation-induced electricity generators.

Study on Coated Zr-V-Cr Getter with Pore Gradient Structure for Hydrogen Masers.

As the core component of satellite navigation, the hydrogen maser needs a high vacuum environment to maintain the stability of the frequency signal. The getter pump, composed of various non-evaporable getters, plays an important role in maintaining the high vacuum. In this paper, the Zr100-xCux (x = 0, 2, 4, 6)/Zr56.97V35.85Cr7.18 getter was studied and the contradiction between sorption performance and mechanical properties was solved. The Zr-V-Cr getter, a better candidate for getter pump, exists for problems which will destroy the high vacuum and affect the service life of the hydrogen maser. To solve the problem of dropping powder from Zr-V-Cr getter, Zr-Cu films were coated on the surface of Zr-V-Cr matrix to obtain the pore gradient structure. After vacuum sintering, the interface showed gradient structure and network change in pore structure from Zr-Cu film to Zr-V-Cr matrix. These characteristic structures made Zr-V-Cr getter have good absorption properties, which is better than a similar product of SAES company and mechanical properties. Because the Zr-Cu film on Zr-V-Cr matrix effectively prevented dropping powders from the matrix, (Zr-Cu)/(Zr-V-Cr) getter solved the problem of dropping powder. The self-developed new getter with pore gradient structure is of great significance for maintaining the high vacuum of hydrogen maser in the future.