In Situ Phase Separation into Coupled Interfaces for Promoting CO₂ Electroreduction to Formate over a Wide Potential Window

Abstract

Bimetallic sulfides are expected to realize efficient CO2 electroreduction into formate over a wide potential window, however, they will undergo in situ structural evolution under the reaction conditions. Therefore, clarifying the structural evolution process, the real active site and the catalytic mechanism is significant. Here, taking Cu2SnS3 as an example, we unveiled that Cu2SnS3 occurred self‐adapted phase separation toward forming the stable SnO2@CuS and SnO2@Cu2O heterojunction during the electrochemical process. Calculations illustrated that the strongly coupled interfaces as real active sites driven the electron self‐flow from Sn4+ to Cu+, thereby promoting the delocalized Sn sites to combine HCOO* with H*. Cu2SnS3 nanosheets achieve over 83.4 % formate selectivity in a wide potential range from −0.6 V to −1.1 V. Our findings provide insight into the structural evolution process and performance‐enhanced origin of ternary sulfides under the CO2 electroreduction.

Multicomponent catalyst design for CO2/N2/NOxelectroreduction

“…Sn 4+ was well protected by the electro-self-flow to Cu + during electrolysis. 35 The delocalization of Sn-based active sites enabled by charge transfer could boost the coupling between H* and HCOO*, thereby accelerating the kinetics of the CO 2 RR and exhibiting excellent electrochemical performance of 83.4% HCOOH formation in a wide potential range (−0.6 V to −1.1 V). The Zhai group also reported a tangible superlattice (Fig.…”

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

“…The X-ray photoelectron spectroscopy (XPS) survey spectra clearly reveal the presence of Sn, Cu, and S elements in the precatalyst (Figure S1 and Table S1, Supporting Information). 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 2f the first 30 min, significantly manifesting that the binding energy of Sn 4+ shifted to a lower energy and the formation of Sn 0 , which is mainly attributed to the alloying and metallization of Sn 4+ under the in situ reconstruction process. 6,34,45 Furthermore, to further reveal the phenomenon of the high proportion of Sn 4+ , XPS characterization with Ar plasma etching was applied to the catalyst. As shown in Figure S7, the atomic content of Sn 0 species on the reconstructed S-CuSn catalyst has been significantly enhanced after Ar plasma etching, and the corresponding atomic contents of Sn 0 and Sn 4+ are calculated to be ca.…”

“…Recent studies have paid much attention on regulating the catalytic activity and energy efficiency of catalysts for the CO 2 RR. However, the morphological and structural evolutions were typically observed under the working conditions, which can further affect their catalytic performances. − Specifically, the dynamic constructions of heterojunction, phase transformation, and single atom may occur during the electrochemical reduction of catalysts. Thus, it is of great significance to elaborate the dynamic evolution process and the in situ construction behavior of electrocatalysts under the working conditions, which would be helpful in understanding the catalytic reaction mechanisms.…”

Recent advances in interface engineering strategy for highly‐efficient electrocatalytic water splitting

“…Strikingly, this work provided a facile fabrication route for materials with mesoporous heterostructures. Furthermore, Zhai's team employed Cu 2 SnS 3 nanosheets as precursors to construct SnO 2 @CuS/Cu 2 O nucleus‐shell nanosheets with a strong coupling interface through in situ rapid phase separation during the electro‐reduction process 94 . Subsequently, the electronic structure of the SnO 2 @CuS/Cu 2 O nanosheets with heterostructure was thoroughly examined, and the strong electronic interaction between SnO 2 and CuS/Cu 2 O at the interface of the heterojunction was confirmed.…”