Boosted formic acid electro-oxidation on platinum nanoparticles and "mixed-valence" iron and nickel oxides

Bilquis Ali Al-Qodami; Sayed Youssef Sayed; Hafsa H Alalawy; Islam M Al-Akraa; Nageh K Allam; Ahmad M Mohammad

doi:10.1039/d3ra03350c

Boosted formic acid electro-oxidation on platinum nanoparticles and "mixed-valence" iron and nickel oxides

RSC Adv. 2023 Jul 11;13(30):20799-20809. doi: 10.1039/d3ra03350c. eCollection 2023 Jul 7.

Authors

Bilquis Ali Al-Qodami^{1

2}, Sayed Youssef Sayed¹, Hafsa H Alalawy¹, Islam M Al-Akraa³, Nageh K Allam⁴, Ahmad M Mohammad¹

Affiliations

¹ Chemistry Department, Faculty of Science, Cairo University Cairo 12613 Egypt ammohammad@cu.edu.eg sysayed@sci.cu.edu.eg.
² Chemistry Department, Faculty of Education and Applied Science, Hajjah University Yemen.
³ Department of Chemical Engineering, Faculty of Engineering, The British University in Egypt Cairo 11837 Egypt.
⁴ Energy Materials Laboratory, School of Sciences and Engineering, The American University in Cairo New Cairo 11835 Egypt.

Abstract

The modification of Pt nanoparticles (nano-Pt, assembled electrochemically onto a glassy carbon (GC) substrate) with hybrid multivalent nickel (nano-NiO_x) and iron (nano-FeO_x) oxide nanostructures was intended to steer the mechanism of the formic acid electro-oxidation (FAO) in the desirable dehydrogenation pathway. This binary modification with inexpensive oxides succeeded in mediating the reaction mechanism of FAO by boosting reaction kinetics "electron transfer" and amending the surface geometry of the catalyst against poisoning. The sequence of deposition was optimized where the a-FeO_x/NiO_x/Pt/GC catalyst (where "a" denotes a post-activation step for the catalyst at -0.5 V in 0.5 mol L^-1 NaOH) reserved the best hierarchy. Morphologically, while nano-Pt appeared to be spherical (ca. 100 nm in average diameter), nano-NiO_x appeared as flowered nanoaggregates (ca. 56 nm in average diameter) and nano-FeO_x (after activation) retained a plate-like nanostructure (ca. 38 nm in average diameter and 167 nm in average length). This a-FeO_x/NiO_x/Pt/GC catalyst demonstrated a remarkable catalytic efficiency (125 mA mg_Pt^-1) for FAO that was ca. 12.5 times that of the pristine Pt/GC catalyst with up to five times improvement in the catalytic tolerance against poisoning and up to -214 mV shift in the FAO's onset potential. Evidences for equipping the a-FeO_x/NiO_x/Pt/GC catalyst with the least charge transfer resistance and the highest stability among the whole investigated catalysts are provided and discussed.