Unveiling pH‐Dependent Adsorption Strength of *CO₂⁻ Intermediate over High‐Density Sn Single Atom Catalyst for Acidic CO₂‐to‐HCOOH Electroreduction

Abstract

The acidic electrochemical CO2 reduction reaction (CO2RR) for direct formic acid (HCOOH) production holds promise in meeting the carbon‐neutral target, yet its performance is hindered by the competing hydrogen evolution reaction (HER). Understanding the adsorption strength of the key intermediates in acidic electrolyte is indispensable to favor CO2RR over HER. In this work, high‐density Sn single atom catalysts (SACs) were prepared and used as catalyst, to reveal the pH‐dependent adsorption strength and coverage of *CO2− intermediates that enables enhanced acidic CO2RR towards direct HCOOH production. At pH = 3, Sn SACs could deliver a high Faradaic efficiency (90.8%) of HCOOH formation and a corresponding partial current density up to –178.5 mA cm−2. The detailed in situ attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopic studies reveal that a favorable alkaline microenvironment for CO2RR to HCOOH is formed near the surface of Sn SACs, even in the acidic electrolyte. More importantly, the pH‐dependent adsorption strength of *CO2− intermediates is unravelled over the Sn SACs, which in turn affects the competition between HER and CO2RR in acidic electrolyte.

Calcium‐Based Metal‐Organic Framework: Detection and Idiosyncratic Removal of Copper by Nano‐Particle Deposition

“…It has already been reported that the adsorption of metal ions from an aqueous solution is pH-dependent. [59,60] Therefore, the optimum pH was evaluated first. The investigation on the optimum pH for achieving maximum adsorption capacities revealed a peak at pH 6.5, as depicted in Figure S10.…”

Revisiting Factors Controlling the Electrochemical CO2 Reduction to CO and HCOOH on Transition Metals with Grand Canonical Density Functional Theory Calculations

“…41−44 Meanwhile, the local pH was found to affect the distributions of carbon-based products during eCO 2 RR on the Cu 45,46 electrodes and Sn SACs. 47 Clearly, the selectivity of eCO 2 RR is controlled by multiple factors ranging from the type of metals, electrolytes, pH, and applied potential, 48,49 making it challenging to clarify the role of a single factor unambiguously. In this work, we are striving to illustrate the metal-dependent selectivity of two-electron eCO 2 RR at different potentials.…”

“…Notably, the influences of electrolytes on the adsorption and reduction of CO 2 have been widely investigated in both experiments and simulations, where the types and compositions of cations and anions played diverse roles in CO 2 reduction. − Meanwhile, the local pH was found to affect the distributions of carbon-based products during eCO 2 RR on the Cu , electrodes and Sn SACs . Clearly, the selectivity of eCO 2 RR is controlled by multiple factors ranging from the type of metals, electrolytes, pH, and applied potential, , making it challenging to clarify the role of a single factor unambiguously.…”

Constructing a Stable Built-In Electric Field in Bi/Bi2Te3 Nanowires for Electrochemical CO2 Reduction Reaction

“…Converting CO 2 into value-added chemicals or fuels is an appealing method for reducing CO 2 emissions and thereby achieving carbon neutrality. − Nevertheless, the inertness and thermodynamic stability of CO 2 severely constrain its conversion efficiency. Electroreduction CO 2 (CO 2 RR) has attracted substantial attention from researchers due to its high conversion efficiency, mild reaction conditions, and elevated energy efficiency. − The specific products formed depend on the number of protons, electrons, and reduction pathways involved, as the CO 2 RR is a multiproton-coupled and multielectron-transfer processes. , By altering the catalytic conditions or reduction pathways, different surface-bound species can generate corresponding reaction intermediates, leading to the formation of different carbon-containing products such as carbon monoxide (CO), formic acid (HCOOH), methane (CH 4 ), and so on. − HCOOH, revered as a high-value CO 2 electroreduction product, is an important raw material in the pharmaceutical and chemical industries, making it one of the most economically viable products in the CO 2 RR process. − In the electrochemical reaction mechanism, HCOOH requires minimal electron transfer during the electroreduction process, which not only simplifies the reduction of CO 2 to HCOOH but also allows for its subsequent conversion into other raw materials such as hydrogen (H 2 ), CO, and methanol (CH 3 OH) through simple catalytic reactions to meet various industrial production needs. − Therefore, the rational design of catalysts and reduction pathways is crucial to the selectivity and yield of the products.…”