Intriguing Catalytic Activity of Surface Active Gold‐Platinum Islands on Nano‐Porous Au in Determining Efficient Direct Formic Acid Oxidation Pathway

Abstract

Gold‐platinum nano‐porous structures (Au100‐xPtx NPoS) with unique surface enriched Au−Pt islands are synthesised through a galvanic replacement strategy from Au100‐xAg2x nano‐alloys with ultra‐low platinum loading (x=1.25, 2.5 and 5). Formic acid oxidation reaction (FAOR) on Au100‐xPtx/C NPoS shows a distinct peak at around 0.5 V related to CO2 formation. A characteristic peak at around 1.5 V increases with increasing FA concentration owing to the direct FAOR by nano‐porous Au centers. FAOR peaks and If/Ib peak current ratios indicates that, Au100‐xPtx/C NPoS facilitates direct FAOR pathway unlike HiSPEC Pt/C (dehydration pathway). Based on the enhanced chrono‐amperometric response, Tafel behaviour and mass activity values, Au97.5Pt2.5/C NPoS (5.5 A/mgPt) reflects as the optimal catalyst for efficient FAOR. The intriguing catalytic role of surface enriched Au−Pt islands present on nano‐porous Au greatly helps in determining the superior FAOR activity in Au97.5Pt2.5/C NPoS towards direct dehydrogenation pathway at ultra‐low Pt content compared to other NPoS and HiSPEC Pt/C catalysts.

The Perfect Imperfections in Electrocatalysts

“…However, because of the uphill reaction, especially the 4‐electron transfer of OER, [25] the commercial electrolyzers require a higher cell potential of 1.8–2.0 V. The high‐cost and low‐abundance of the noble metal based benchmark catalysts such as IrO 2 , RuO 2 for OER, and Pt for HER, limit their large‐scale commercial applications Herein, the low‐cost transition metal based electrocatalysts have been researched extensively over the years [7,26–29] . The best performing catalyst systems are synthesized at the nanoscale dimensions for introducing an abundance of surface active catalytic sites [30] . When these catalyst nanostructures are synthesized by a wide range of synthesis methods, the introduction of undercoordinated surface sites, lattice strain, atom/ion vacancies, dislocations and GBs become inevitable [31,32] .…”

“…[7,[26][27][28][29] The best performing catalyst systems are synthesized at the nanoscale dimensions for introducing an abundance of surface active catalytic sites. [30] When these catalyst nanostructures are synthesized by a wide range of synthesis methods, the introduction of undercoordinated surface sites, lattice strain, atom/ion vacancies, dislocations and GBs become inevitable. [31,32] The shape specific synthesis can improve the surface-active sites for boosting the electrochemical activities through the creation of concave defects or hollow and framelike NPs.…”