• Energy Research

Polarized hydroxyapatite (HAp) scaffolds with customized architecture at the nanoscale have been presented as a green alternative to conventional catalysts used for carbon and dinitrogen fixation. HAp printable inks with controlled nanoporosity and rheological properties have been successfully achieved by incorporating Pluronic hydrogel. Nanoporous scaffolds with good mechanical properties, as demonstrated by means of the nanoindentation technique, have been obtained by a sintering treatment and the posterior thermally induced polarization process. Their catalytic activity has been evaluated by considering three different key reactions (all in the presence of liquid water): (1) the synthesis of amino acids from gas mixtures of N2, CO2, and CH4; (2) the production of ethanol from gas mixtures of CO2 and CH4; and (3) the synthesis of ammonia from N2 gas. Comparison of the yields obtained by using nanoporous and nonporous (conventional) polarized HAp catalysts shows that both the nanoporosity and water absorption capacity of the former represent a drawback when the catalytic reaction requires auxiliary coating layers, as for example for the production of amino acids. This is because the surface nanopores achieved by incorporating Pluronic hydrogel are completely hindered by such auxiliary coating layers. On the contrary, the catalytic activity improves drastically for reactions in which the HAp-based scaffolds with enhanced nanoporosity are used as catalysts. More specifically, the carbon fixation from CO2 and CH4 to yield ethanol improves by more than 3000% when compared with nonporous HAp catalyst. Similarly, the synthesis of ammonia by dinitrogen fixation increases by more than 2000%. Therefore, HAp catalysts based on nanoporous scaffolds exhibit an extraordinary potential for scalability and industrial utilization for many chemical reactions, enabling a feasible green chemistry alternative to catalysts based on heavy metals.

Polarized hydroxyapatite (HAp) scaffolds with customized architecture at the nanoscale have been presented as a green alternative to conventional catalysts used for carbon and dinitrogen fixation. HAp printable inks with controlled nanoporosity and rheological properties have been successfully achieved by incorporating Pluronic hydrogel. Nanoporous scaffolds with good mechanical properties, as demonstrated by means of the nanoindentation technique, have been obtained by a sintering treatment and the posterior thermally induced polarization process. Their catalytic activity has been evaluated by considering three different key reactions (all in the presence of liquid water): (1) the synthesis of amino acids from gas mixtures of N2, CO2, and CH4; (2) the production of ethanol from gas mixtures of CO2 and CH4; and (3) the synthesis of ammonia from N2 gas. Comparison of the yields obtained by using nanoporous and nonporous (conventional) polarized HAp catalysts shows that both the nanoporosity and water absorption capacity of the former represent a drawback when the catalytic reaction requires auxiliary coating layers, as for example for the production of amino acids. This is because the surface nanopores achieved by incorporating Pluronic hydrogel are completely hindered by such auxiliary coating layers. On the contrary, the catalytic activity improves drastically for reactions in which the HAp-based scaffolds with enhanced nanoporosity are used as catalysts. More specifically, the carbon fixation from CO2 and CH4 to yield ethanol improves by more than 3000% when compared with nonporous HAp catalyst. Similarly, the synthesis of ammonia by dinitrogen fixation increases by more than 2000%. Therefore, HAp catalysts based on nanoporous scaffolds exhibit an extraordinary potential for scalability and industrial utilization for many chemical reactions, enabling a feasible green chemistry alternative to catalysts based on heavy metals.

Electrically polarized amorphous silica (aSiO2) is demonstrated to be an efficient and viable metal-free heterogeneous catalyst for the conversion of CO2 into valuable chemical products.

Electrically polarized amorphous silica (aSiO2) is demonstrated to be an efficient and viable metal-free heterogeneous catalyst for the conversion of CO2 into valuable chemical products.

The conversion of methane into useful chemicals has an enormous interest from both economic and social points of view as it is an important feedstock in chemical industry and is...

The conversion of methane into useful chemicals has an enormous interest from both economic and social points of view as it is an important feedstock in chemical industry and is...

The selective production of ethanol has been achieved by fixing carbon from CO2 and CH4. The reaction, which is based on the electro-reduction of CO2, is catalysed by polarized hydroxyapatite and occurs under mild reaction conditions.

The selective production of ethanol has been achieved by fixing carbon from CO2 and CH4. The reaction, which is based on the electro-reduction of CO2, is catalysed by polarized hydroxyapatite and occurs under mild reaction conditions.