Dinorah Ivette Rodríguez Otamendi

You want to make carbon-supported palladium catalyst nanoparticles. Your process has two stages. In the first, you get platinum nanoparticles. In the second step, you need to "plant" the nanoparticles onto the substrate. Or you need to take nanocarbon tubes. Better oxidized. Your substrate should have a large specific area. For this, porous alumina or silicon oxide is usually used. Write the chemical reaction and calculate the amount of citric acid for reduction and take an excess so that the rest of the acid is used to bond the palladium nanoparticles to the substrate. After that, you need to separate the catalyst, rinse and determine its composition. After that, if this does not spoil your plans, it must be calcined at a temperature of 500 degrees. For an example, see our article on this topic.

Article Preparation of Nanomaterials from Aqueous Solutions Imitatin...

Hello..the usual method to prepare nanoparticles with citrate as reducing agent is to mix the metal solution (palladium, gold etc) with the citrate solution at under reflux at boiling temperature.. 10 minutes of reaction at room temperature it may not be enough to reach full reduction!

Dinorah Ivette Rodríguez Otamendi

It seems you want to make a supported Pd/C or similar (catalyst?) material as opposed to a colloidal suspension (sol) of Pd particles. Citrate reduction (Turkevich) process normally used to make colloidal suspensions rather than nanoparticles on a substrate. For making a (say) 5% Pd/C material I would not use the stirred reactor approach but rather use an approach for making heterogeneous catalysts. This would saturate the pores of the carbon with a solution of your acidic solution of palladium chloride and then reduce with H2 or (5/10%) hydrazine hydrate. Typically you can produce Pd in the 5 - 10 nm (by number) size region supported on the substrate by this process. You'll need a knowledge of the pore volume of the substrate. I used both the latter reductants in my Ph.D back when dinosaurs ruled the earth. A methodology is provided in the previous RG question:

https://www.researchgate.net/post/Calculation_on_Percent_Pt_doped_on_TiO2_Kronos

BTW, I'd avoid borohydride reduction.

Dear Dinorah,

just in case that this question is still of interest to you: Are you not following a literature method? In any case I suggest that you use the "Publications" section of RG to find and access relevant literature references about this topic. Many helpful articles have been posted by RG members, some of them even as public full texts. This is the case for example with the following very interesting paper:

Hydrogenation on Palladium Nanoparticles Supported by Graphene Nanoplatelets

Article Hydrogenation on Palladium Nanoparticles Supported by Graphe...

This article can be freely downloaded as pdf file. The authors report here a straightforward method for preparing Pd nanoparticles deposited on graphene nanoplatelets. Formaldehyde was used here as reducing agent to form the Pd nanoparticles.

For more general information please also have a look at the following very instructive review article:

Palladium-Based Nanomaterials: Synthesis and Electrochemical Applications

Article Palladium-Based Nanomaterials: Synthesis and Electrochemical...

The review article has not yet been posted by the authors as public full text on RG. However, both authors have RG profiles. Thus you can easily contact them via RG and request the full text directly from one of them. Normally authors are very helpful when they receive such requests.

Good luck with your research and best wishes, Frank Edelmann

Thanks to everyone for all the advices posted.

Hi everyone,

Care should be taken when preparing Pd nanoparticles in the presence of citrate ions and a strong reducing agent such as NaBH4: the final material may not be a pure Pd phase; rather, a carbide phase (PdCx), a hydride (PdHy) or even a mixed PdCxHy) may be present. In all those cases, a dilation of the lattice parameter is observed from XRD measurements. Further information and more references may be found in our previous paper (Article On the lattice dilation of palladium nanoparticles and a new...

Eduardo G. Ciapina To add to your remarks, I would never consider NaBH4 reduction for making Pd, Pt, or Au nanoparticles. In my experience there is extensive intractable B contamination which cannot be removed by washing and can act as a catalyst poison.

Alan F Rawle, sometimes the presence of B can increase the reaction rate; this effect was already observed in electrochemical reactions:

1) C.W.A. Chan, A.H. Mahadi, M.M.-J. Li, E.C. Corbos, C. Tang, G. Jones, W.C.H. Kuo, J. Cookson, C.M. Brown, P.T. Bishop, S.C.E. Tsang, Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation, Nat. Commun. 5 (2014) 5787, https://doi.org/10.1038/ncomms6787

2) T.T. Vo Doan, J. Wang, K.C. Poon, D.C.L. Tan, B. Khezri, R.D. Webster, H. Su, H. Sato, Theoretical modelling and facile synthesis of a highly active boron-doped pal- ladium catalyst for the oxygen reduction reaction, Angew. Chem. Int. Ed. 55 (2016) 6842–6847, https://doi.org/10.1002/anie.201601727