Electro-Design of Bimetallic PdTe Electrocatalyst for Ethanol Oxidation: Combined Experimental Approach and Ab Initio Density Functional Theory (DFT)-Based Study

Andile Mkhohlakali; Xolile Fuku; Min Ho Seo; Mmalewane Modibedi; Lindiwe Khotseng; Mkhulu Mathe

doi:10.3390/nano12203607

Electro-Design of Bimetallic PdTe Electrocatalyst for Ethanol Oxidation: Combined Experimental Approach and Ab Initio Density Functional Theory (DFT)-Based Study

Nanomaterials (Basel). 2022 Oct 14;12(20):3607. doi: 10.3390/nano12203607.

Authors

Andile Mkhohlakali^{1

2}, Xolile Fuku³, Min Ho Seo⁴, Mmalewane Modibedi⁵, Lindiwe Khotseng², Mkhulu Mathe⁶

Affiliations

¹ Analytical Chemistry Division, Mintek, 200 Malibongwe Drive, Randburg 2194, South Africa.
² Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa.
³ Institute of Nanotechnology and Water Sustainability, College of Science, Engineering and Technology, University of South Africa, Florida Science Campus, Roodepoort 1710, South Africa.
⁴ Department of Nanotechnology Engineering, Pukyong National University, 45 Yongso-ro, Nam-gu, Busan 48547, Korea.
⁵ Council for Scientific and Industrial Research (CSIR), Energy Center, Pretoria 0012, South Africa.
⁶ Department of Chemistry, ICES, CSET, University of South Africa, Florida Science Campus, Roodepoort 1710, South Africa.

Abstract

An alternative electrosynthesis of PdTe, using the electrochemical atomic layer deposition (E-ALD) method, is reported. The cyclic voltammetry technique was used to analyze Au substrate in copper (Cu²⁺), and a tellurous (Te⁴⁺) solution was used to identify UPDs and set the E-ALD cycle program. Results obtained using atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques reveal the nanometer-sized flat morphology of the systems, indicating the epitaxial characteristics of Pd and PdTe nanofilms. The effect of the Pd:Te ratio on the crystalline structure, electronic properties, and magnetic properties was investigated using a combination of density functional theory (DFT) and X-ray diffraction techniques. Te-containing electrocatalysts showed improved peak current response and negative onset potential toward ethanol oxidation (5 mA; -0.49 V) than Pd (2.0 mA; -0.3 V). Moreover, DFT ab initio calculation results obtained when the effect of Te content on oxygen adsorption was studied revealed that the d-band center shifted relative to the Fermi level: -1.83 eV, -1.98 eV, and -2.14 eV for Pd, Pd₃Te, and Pd₃Te₂, respectively. The results signify the weakening of the CO-like species and the improvement in the PdTe catalytic activity. Thus, the electronic and geometric effects are the descriptors of Pd₃Te₂ activity. The results suggest that Pd₂Te₂ is a potential candidate electrocatalyst that can be used for the fabrication of ethanol fuel cells.

Keywords: DFT calculation; PdTe nanofilms; ethanol oxidation reaction; oxygen binding energy; underpotential deposition.

Abstract

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