The Relationships among Hydrogen Adsorption, CO Stripping, and Selectivity of CO₂ Reduction on Pd Nanoparticles

Abstract

The low formation overpotential and strong adsorption ability of CO on palladium surface sites constrain the lower potential limit and current density of the electrochemical reduction of CO2 (CO2ER) to formate on Pd although this reaction has been considered one of the most effective methods for CO2 recycling. Among various factors, the participation of adsorbed hydrogen atoms seems to be a key factor affecting the selectivity of CO2ER on Pd. This article discusses the relationship between the selectivity and hydrogen adsorption on the Pd nanoparticles/carbon (Pd/XC72) catalyst through two kinds of systems: gas diffusion electrode (GDE) and rotating ring disk electrode (RRDE). The main product of the CO2ER on Pd/XC72 is changed from formate to CO when both the terrace and step sites of Pd particles are under a low coverage of adsorbed H atoms. In addition, the progress of CO self-poisoning on the Pd/XC72 catalyst and the peak corresponding to the oxidation of COOH* on the Pt ring electrode are clearly observed by the electrochemical analysis methods. The high selectivity of CO generation from the CO2ER on the Pd/XC72 catalyst is attributed to the progressive adsorption of CO which inhibits the participation of Hads during the CO2ER.

Accelerating Pd Electrocatalysis for CO2-to-Formate Conversion across a Wide Potential Window by Optimized Incorporation of Cu

“…Obviously, the smaller peak area suggests less CO accumulation on Pd 82 Cu 18 relative to pure Pd during the CO 2 RR. Additionally, it is well-known that electro-oxidation of pre-adsorbed CO, so-called CO stripping, is an effective strategy to probe the CO tolerance ability. , If CO adsorbed on Pd sites with deferred removal, it could result in an accumulation of CO on the catalyst surface, leading to Pd poisoning. Thus, in order to further support the CO removal capacity of the Pd 82 Cu 18 catalysts, we also performed CO stripping measurements on both Pd 82 Cu 18 and Pd.…”

Durable Electrocatalytic CO2 Reduction Using Intermetallic Compound PdIn Nanoparticles and Their Application to a Solar Energy Harvesting System

“…The same phenomenon has been reported in the literature. 21 The tendency to stop HCOOH formation was also observed in an aqueous K 2 SO 4 -based solution saturated with CO 2 (Figure S11). Most importantly, this tendency was opposite to that of PdIn/KB regardless of the aqueous electrolytes saturated with CO 2 , resulting in steady formations of CO and HCOOH (Figure 4b and Figures S11 and S12).…”

Intercalated Gold Nanoparticle in 2D Palladium Nanosheet Avoiding CO Poisoning for Formate Production under a Wide Potential Window

“…In this work, when the applied potential is below −0.35 V RHE , the PdH x phase is reserved and thus the CO production is effectively inhibited on Au x NP-in-PdNS. CO 2 could then enter into a Pd–H bond and form the HCOO* intermediate for producing formate with outstanding selectivity and long-term stability (Figure c). ,− On the contrary, the CO production still occurs on the Pd NS via the formation of COOH* and CO* intermediates. The produced CO could be adsorbed on the Pd surface and contaminate α-PdH x , resulting in the deactivation of Pd NS catalyst and the obvious production of CO instead of formate under the potential below −0.35 V (Figure d). ,,, …”