Stabilizing indium sulfide for CO2 electroreduction to formate at high rate by zinc incorporation

Abstract

Recently developed solid-state catalysts can mediate carbon dioxide (CO2) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant current densities of > 200 milliamperes per square centimeter (mA cm−2), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn2S4 catalyst can reduce CO2 to formate with 99.3% Faradaic efficiency at 300 mA cm−2 over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which “locks” sulfur—a catalytic site that can activate H2O to react with CO2, yielding HCOO* intermediates—from being dissolved during high-rate electrolysis.

Customizing the microenvironment of CO2 electrocatalysis via three‐phase interface engineering

“…Consequently, researchers focus on the development of various catalysts with high activity. [9][10][11] Similarly, substantial efforts have been invested in the fabrication of different CRR catalysts, including single-atom, 12 alloy, 13,14 surface oxidation state, [15][16][17] grain boundaries, 18 solid solutions, 19 morphologies, 20,21 chemical composition, 22 and crystal facet engineering. 23 Nevertheless, differently to thermal catalysis, since CRR occurs on a gas/solid/liquid three-phase interface (Figure 1C), 24 its reactivity is also sensitive to the local reaction environment of the catalysts, such as the specific electrolyte, 25 pH, 26 presence of metal cations, 27 surface structure and composition of the catalyst, 28 and some other factors.…”

In Situ Dynamic Construction of a Copper Tin Sulfide Catalyst for High-Performance Electrochemical CO2 Conversion to Formate

“…The high-resolution XPS spectra of Sn 3d for the precatalyst show two characteristic peaks at the binding energy of 495.7 and 487.3 eV with a separation of 8.4 eV (Figure g), which can be assigned to Sn 3d 3/2 and Sn 3d 5/2 , respectively, − suggesting the Sn 4+ state in the precatalyst. The Cu 2p spectrum exhibits four obvious peaks of Cu 2p 1/2 (951.7, 952.5 eV) and Cu 2p 3/2 (931.8, 932.6 eV) with a separation of 19.9 eV, indicating the +2 and +1 oxidation states of Cu species for Cu 2 SnS 3 and CuS in the precatalyst, respectively (Figure h). ,− The high-resolution S 2p spectrum can be deconvoluted into two components, corresponding to S 2p 1/2 (163.1 eV) and S 2p 3/2 (161.7 eV) (Figure i). ,, Additionally, the elemental ratio of the precatalyst was also investigated by ICP-MS characterization, in which the atomic ratios of Cu/Sn and S/Sn are close to 2 and 3, respectively. (Figure S2, Supporting Information).…”

“…The electrochemical conversion of carbon dioxide (CO 2 ) to carbon-based fuels and chemical feedstocks utilizing renewable electricity contributes to alleviating the current environmental problems of global warming and energy crisis and further reducing the growing emission of CO 2 to achieve a carbon-neutral cycle. − Recently, considerable studies have been devoted to producing valuable products from the electrochemical CO 2 reduction reaction (CO 2 RR). − However, due to the multiple electron transfer reaction pathways of the CO 2 RR, a diverse range of gaseous and liquid products ranging from C 1 to C 3 can be obtained during the process of the CO 2 RR, ,, such as carbon monoxide (CO), methane (CH 4 ), formic acid (HCOOH), ethylene (C 2 H 4 ), ethanol (C 2 H 5 OH), and n-propanol (C 3 H 8 O) . Among them, HCOOH has been considered as one of the most economical products, which can be used as a hydrogen energy carrier and chemical fuel. , In addition, as a competitive transformational form with respect to traditional chemical engineering processes, the electrochemical conversion of CO 2 to formate (HCOO – ) can be most likely industrialized owing to the high selectivity and activity .…”

CO2 Conversion at High Current Densities: Stabilization of Bi(III)-Containing Electrocatalysts under CO2 Gas Flow Conditions

“…Formate is another commodity chemical of high value that can be formed as a product of the CO 2 RR. 25,26 As recently noted by Chen et al, 27 it is the liquid nature of the formate/formic acid product that enables the downstream product separation following primary electrolysis to be conducted with less effort, thus enhancing the profitability of the overall production process. Existing and potential future applications of formate/formic acid concern formic acid fuel cells, 28−30 related hydrogen storage technologies, 31 the chemical depolymerization of lignin (biomass valorization), 32 and its usage as a silage additive.…”