Recent Progress of Vacancy Engineering for Electrochemical Energy Conversion Related Applications

Electrochemical CO2 conversion into fuels is highly desirable to achieve carbon artificial cycles. Among electrocatalyst candidates, earth-abundant tin is subject to unsatisfied efficiency and selectivity. In this work, atomically-dispersed Sn nanoclusters modified with the trace of sulfur doping are proposed to efficiently electroreduce CO2 to C1 chemicals. This electrocatalyst is in situ derived from bis(benzene-1,2-dithiolato). It exhibits a high Faradaic efficiency (90%) for carbonaceous products at a moderate overpotential (0.75 V). Importantly, it is exploited for the formate formation with unprecedented partial current density (90 mA cm−2) and long-term stability (50 h) using the flow cell, better than most Sn-based catalysts. Electrochemical experiments and theoretical calculations manifest the promoting effect of trace sulfur on Sn nanoclusters, which stabilizes the *HCOOH intermediate and favors CO2 electroreduction. Hence, it emphasizes the importance of dopants and charge modulating for performance enhancement. This work unfolds a promising candidate for Sn electrocatalysts towards CO2 electroreduction. 

Atomically dispersed Sn modified with trace sulfur species derived from organosulfide complex for electroreduction of CO2

Electrochemical CO2 conversion into fuels is highly desirable to achieve carbon artificial cycles. Among electrocatalyst candidates, earth-abundant tin is subject to unsatisfied efficiency and selectivity. In this work, atomically-dispersed Sn nanoclusters modified with the trace of sulfur doping are proposed to efficiently electroreduce CO2 to C1 chemicals. This electrocatalyst is in situ derived from bis(benzene-1,2-dithiolato). It exhibits a high Faradaic efficiency (90%) for carbonaceous products at a moderate overpotential (0.75 V). Importantly, it is exploited for the formate formation with unprecedented partial current density (90 mA cm−2) and long-term stability (50 hours) using the flow cell, better than most Sn-based catalysts. Electrochemical experiments and theoretical calculations manifest the promoting effect of trace sulfur on Sn nanoclusters, which stabilizes the *HCOOH intermediate and favors CO2 electroreduction. Hence, it emphasizes the importance of dopants and charge modulating for performance enhancement. This work unfolds a promising candidate for Sn electrocatalysts towards CO2 electroreduction.

Atomically Dispersed Sn Modified with Trace Sulfur Species Derived from Organosulfide Complex for Electroreduction of CO2

Development of porous catalysts for electrochemical reduction of CO₂ relies on methodological innovation in regard to both rational structure design and feasible preparation. Organically directed selenidometalates emerge as a type of promising crystalline precursors for their homogeneously distributed templates that can undergo precise thermolysis and volatilization. Herein, we report the facile thermally driven conversion of choline-templated selenidostannate, [(CH₃)₃N(CH₂)₂OH]₂[Sn₃Se₇]·H₂O (Ch-Sn₃Se₇), into a series of mesoporous SnO₂ (P-SnO₂) materials as high-performance electrocatalysts for CO₂ reduction. Variations of particle morphology/size and surface area with calcination time were systematically investigated and correlated to the electrocatalytic activity and product selectivity. The optimal electrode loaded with P-SnO₂-0 min exhibits a high faradic efficiency (up to 94.5%), a large partial current density (∼11.5 mA cm–²), and excellent long-term stability (100 h) for transforming CO₂ into useful C₁ products (HCOOH + CO) at −1.06 V vs reversible hydrogen electrode (RHE), comparable to the top-level Sn-based catalysts. A detailed investigation into the long-term electrolysis revealed a gradual fragmentation of the pristine SnO₂ nanoparticles along with partial SnO₂–SnO–Sn self-reduction, which contributes to increased active sites that account for the highly selective and stable electrolysis process. This work provides a facile and low-cost templating method for the preparation of porous materials and gives some deeper insights into the course of the catalytic reaction that are of considerable industrial significance.

Conversion of Organically Directed Selenidostannate into Porous SnO2 Exhibiting Effective Electrochemical Reduction of CO2 to C1 Products

In general, commercial ZnO owns the poor selectivity and activity toward electroreduction CO2 to formate. In contrast, the numbers of Sn‐based nanomaterials are reported as excellent electrocatalysts for formate production, however, the metallic Sn is more expensive than Zn. In this study, it is demonstrated that an atomically dispersed Sn on a tensile‐strained ZnO nanosheet (Sn SA/ZnO) shows dramatically improved activity and selectivity for formate production over a wide potential window compared with that of commercial ZnO. Especially, Sn SA/ZnO exhibits 205‐fold mass activity enhancement than the commercial Sn at −1.7 V versus reversible hydrogen electrode normalized with element Sn. The experimental measurements combined with theoretical calculations revealed that Sn SA/ZnO can effectively capture and activate CO2 by its exposed double‐active sites (Sn and O), while the tensile strain on its surface boosts the catalytic selectivity by strengthening the adsorption of the *HCOO intermediate for the electrochemical reduction of CO2 to formate.

Linlin Wu

Papers

Boosting carbon dioxide electroreduction to C1 feedstocks via theory-guided tailoring oxygen defects in porous tin-oxide nanocubes