Towards more active and stable PdAgCr electrocatalysts for formic acid electrooxidation: The role of optimization via response surface methodology

Abstract

In this study, multiwall carbon nanotube (MCNT)-supported Pd (Pd/MWCNT) catalysts are prepared by using NaBH 4 reduction method. In order to maximize the oxidation and reduction of H 2 SO 4 , synthesis conditions (Pd ratio, molar ratio of NaBH 4 /K 2 PdCl 4 , volume of deionized water, and duration of agitation) are optimized by using response surface methodology (RSM). The optimum synthesis conditions are determined as 58.2% of Pd by weight, 154.6 molar ratio of NaBH 4 to K 2 PdCl 4 , 19.48 mL of deionized water, and 186.16 min of agitation duration. The effect of electrochemical measurement conditions on the oxidation kinetics of Pd/MWCNT is also investigated by RSM. The optimum electrochemical measurement conditions are found as 10 μL of catalyst mixture, 90°C of H 2 SO 4 solution, and 5.5 M H 2 SO 4 . The Pd/MWCNT, Pd 50 Ag 50 /MWCNT, and Pd 65.6 Ag 33.6 Cr 0.80 /MWCNT catalysts prepared under optimized conditions are characterized by using X-ray diffraction, transmission electron microscopy, N 2 adsorption-desorption, and inductively coupled plasma mass spectrometry. The crystallite sizes of these catalysts are found as 4.85, 5.66, and 5.26 nm for Pd/MWCNT, Pd 50 Ag 50 /MWCNT, and Pd 65.6 Ag 33.6 Cr 0.80 /MWCNT catalysts, respectively. Isotherms of all these catalysts are found to be similar to Type V isotherms with H3 hysteresis loop. The average particle size of Pd 50 Ag 50 / MWCNT and Pd 65.6 Ag 33.6 Cr 0.80 /MWCNT catalysts are determined as 5.2 and 9.2 nm, respectively. Electrochemical performance of as-prepared catalysts is evaluated by using cyclic voltammetry and chronoamperometry. The formic acid electrooxidation (FAEO) activities are found as 18.9, 27.8, and 51.6 mA/cm 2 for Pd/MWCNT, Pd 50 Ag 50 /MWCNT, and Pd 65.6 Ag 33.6 Cr 0.80 /MWCNT, respectively. Pd 65.6 Ag 33.6 Cr 0.80 /MWCNT shows the highest activity and stability. Optimization of synthesis conditions and electrochemical measurement parameters allow us to obtain very good electrochemical activity and stability for FAEO reaction compared with anode catalysts in the literature.

Interaction effect of process parameters and Pd‐electrocatalyst in formic acid electro‐oxidation for fuel cell applications: Implementing supervised machine learning algorithms

“…The Pd‐based electrocatalyst displayed a high potential of current density in the DFAFCs at optimized conditions. Similarly, Ulas et al 27 employed response surface methodology to optimize parameters such as Pd ratio, the molar ratio of NaBH 4 /K 2 PdCl 4 , volume of deionized water, and duration of agitation in a formic acid electrooxidation process. The operating conditions were optimized to obtain maximum performance of the formic acid electrooxidation.…”

Prediction of electrocatalyst performance of Pt/C using response surface optimization algorithm‐based machine learning approaches

“…16 In the last few years, RSM has been used to reveal mathematical modeling and show the synergetic effects of independent parameters in numerous catalyst synthesis processes. [17][18][19] To investigate the effect of process parameters and their interactions on output, DOE methods were widely preferred by the researchers. These methods also give a mathematical model between the independent parameters to determine optimum condition.…”

The preparation, characterization, and electrooxidation of colloidal palladium modified poly(methacrylic acid) hydrogel as formic acid fuel cell anode catalyst

“…FCs, which convert chemical energy into electrical energy, are environmentally friendly, long-lasting technology that does not harm nature. 19 Direct liquid-fed FCs (DLFCs), employing fluid fuels such as methanol, 67,68 glucose, 22,69 hydrazine, 70 ethanol, 11,71 glycerol, 72 ethylene glycol, 73,74 and formic acid (HCOOH, FA), 23,75 are preferable because DLFCs do not have the disadvantages of hydrogen FCs like employing a pure gas tank or fuel reforming. 76,77 FA is a preferred and promising fuel due to its advantages such as portable, low cost, clean liquid fuel.…”