Thermally processed Ni-and Co-struvites as functional materials for proton conductivity

Abstract

Here, we describe how to synthesise proton-conductive transition metal phosphates (TMPs) by direct thermal processing of precursor M-struvites, NH4MPO4·6H2O, with M = Ni2+, Co2+. In the as-derived TMP phases their...

Investigation of Morphology, Optical and Electronic Ac Conduction of the Olivine Manganite Compound: NaMnPO4

“…[55] As the temperature rises, their diameters decline, suggesting that the conduction mechanism is thermally activated. [56] Through the Z View software, these semicircles were accurately improved using an electrical equivalent circuit identified as (R g //CPE g + R gb //CPE gb ) + CPE ele , as depicted in insert Figure 10, where R g = the resistivity of grains, R gb = the grain boundaries resistance, CPE g reflect the grains' capacity phase components, CPE gb is the grain boundaries' capacity phase components and CPE is the effect electrod. The equivalent circuit parameters for the NaMnPO 4 sample are given in table 2.…”

Nonclassical Crystallization Pathway of Transition Metal Phosphate Compounds

“…Therefore, coprecipitation of phosphate and transition metal-bearing phases from various waste streams of agricultural, industrial, or mining origin (tailings, sludge, wastewaters) is a viable extraction and recycling method to yield transition metal phosphates (TMPs). , Such materials could be further upcycled into processed, higher value compounds suitable for applications. For example, transition metal phosphates, such as Zr, Sn, Ni, or Co phosphates, garnered attention as low-cost, chemically stable, and tunable proton conductors for fuel cells. − However, to effectively harvest metal and phosphate in the form of TMPs and convert them to functional materials, one must elucidate their nucleation and crystallization pathways from aqueous solutions. Although the synthesis and precipitation of Mg or Ca phosphate-bearing phases are relatively well-characterized, − investigations of the crystallization of transition metal phosphate materials are scarce and focus on mineralogical aspects .…”

Non-classical crystallization pathway of transition metal phosphate compounds

“…Such materials could be further upcycled into processed, higher value compounds suitable for applicational use. For example, transition metal phosphates such as Zr- 6 , Sn-7 , Ni-or Co- 8 phosphates garnered attention as low-cost, chemically stable and tunable proton conductors for fuel cells [9][10][11][12][13][14][15][16] . However, to effectively harvest metal and phosphate in a form of TMPs and convert them to functional materials, one needs to elucidate their nucleation and crystallization pathways from aqueous solutions.…”