Due to their relatively low price, high surface area and versatile physic-chemical properties,
conductive carbon materials are considered among the most promising supports of electroactive
species and/or catalysts for different electrochemical devices, like supercapacitors, fuel cells,
batteries, sensors, etc. [1]. However, in these applications, carbon supports are usually subjected to
oxidation and/or corrosion processes, which can be promoted by the supported electroactive species
and/or catalysts [2]. In this sense, although the surface functionalities of carbons seem to play a key
role on their electrochemical response and stability, their influence in the presence of electroactive
catalysts is still controversial. Particularly, the effect of phosphorous groups has been never
reported. In this work, the influence of different oxygen and phosphorous functionalities on the
electrochemical behavior of Pt- and Pd-supported activated carbons (ACs) has been studied.
Various ACs showing similar surface areas (ca. 1400-1500 m2/g) and a rich variety of surface
chemistry, with oxygen and phosphorous-like surface groups, were obtained by physical (CO2)
(HAG800 support) or chemical
(H3PO4) (HA3500 support)
activation of olive stone. The
ACs were used as support of
Pd, Pt and Pd/Pt catalysts (Fig
1a), with nominal loadings of
0.5-1.0 wt%, by using the
incipient-wetting impregnation
method. The samples were
characterized by N2 and CO2
adsorption, TEM, XRD, XPS,
TPD experiments and different
electrochemical techniques.
Although the supported metals
promote carbon electroxidation and/or corrosion (see the higher oxidation currents for the metalloaded
sample – Fig 1b), the presence of surface phosphorous groups (HA3500-M samples) results
in lower oxidation currents than in the case of P-free samples (HAG800-M samples) (Fig. 1.b).
These results are in agreement with the oxidation resistance induced by phosphorous groups in
oxidizing gas phase at high temperatures [3], and may support the statement that these phosphorous
groups could enhance the durability of carbon-supported metal electrocatalysts for different
electrochemical applications.Universidad de Málaga. Campus de Excelencia Andalucía Tech
