Permanently polarized hydroxyapatite, an outstanding catalytic material for carbon and nitrogen fixation

Abstract

Hydroxyapatite (HAp) is a well-known ceramic material widely used in the biomedical field. This review summarizes the very recent developments on permanently polarized HAp (pp-HAp), a HAp variety with tuned...

Hydroxyapatite-based catalysts for CO2fixation with controlled selectivity towards C2 products. Phenomenal support or active catalyst?

“…S1, † further examination was performed to ensure that the HAp content of s-(s-HAp/TiO 2 ) does not present signicant structural differences with respect to the HAp catalyst reported in the literature, including the generation of OH − vacancies obtained by means of Raman spectroscopy (see ESI †). 14,21 Fig. 1b compares the WAXD diffractograms of s-(HAp/TiO 2 ) and s-(s-HAp/TiO 2 ).…”

“…This feature conrms the success of the polarization process (see ESI †) and, therefore, the correct incorporation of TiO 2 NPs onto p-HAp. 14 3.1.2 Morphological considerations. The incorporation of TiO 2 NPs was performed by drop casting TiO 2 NPs from an aqueous suspension (37.1 mg L −1 ).…”

“…[11][12][13] Indeed, its unique open crystallographic structure and tunable stoichiometry allow high isomorphic substitutions or generation of vacancies (Ca 2+ or OH − ) resulting in customized surface charge accumulation for boosted catalytic efficiencies. 11,14 Therefore, the incorporation of Cu, Au, Pd, Co or TiO 2 , among others, has been successfully reported for the reforming of methane, CO 2 reduction to alcohol and aromatic syntheses. 11,13,[15][16][17][18][19] However, only in the last few years signicant progress has been made on the enhancement of the electrical properties of Hap, which has allowed the successful conversion of CO 2 into ethanol (with a selectivity up to 93% comparable to the ones reported using MOF catalysts) under very mild conditions.…”

“…Motivated by the recent knowledge reported on the fundamentals of p-HAp, 14 in this work we propose a change in the paradigm studying a catalytic system composed of TiO 2 nanoparticles (NPs) deposited on p-HAp, where p-HAp is not only considered as a mechanical support but has been put in the spotlight for catalyst preparation and as an active catalytic part. Therefore, in this study we exploit the catalyst–support duality shown by p-HAp for the challenging fixation of CO 2 into C2 products by providing and discussing adequate procedures and characterization techniques to obtain HAp-based catalysts where the enhanced catalytic properties arising from p-HAp are not lowered.…”

Decarbonization of Polluted Air by Solar‐Driven CO2 Conversion into Ethanol Using Polarized Animal Solid Waste as Catalyst

“…This is the generation of active binding sites in polarized bones identical to those found in synthetic p‐HAp, which was proved to exhibit a very active catalytic role in the transformation of CO 2 into valuable chemical products. [ 15 ] The obtaining of catalytic p‐HAp from the natural source employed in this work (solid animal waste) is demonstrated below using wide‐angle X‐ray diffraction (WAXD) and Raman spectroscopy.…”