材料导报:能源(英文)最新文献

Cu-based electrocatalysts have become the focus in the field of electrochemical CO₂ reduction reaction (ECO₂RR) due to their ability to produce multicarbon products. However, the research on generating single carbon products with higher economic feasibility via ECO₂RR based on Cu-based electrocatalysts is rather rare, and the roles of the surface architecture and oxides of the electrocatalysts have not been explained exactly. In this work, a two-step method including thermal oxidation and electroreduction is proposed to introduce Cu⁺ into pure Cu foil to form Cu₂O/Cu electrocatalyst. By regulating the surface composition and morphology of the electrocatalyst in this way, the activity of ECO₂RR to C₁ products has been greatly improved. The Faradaic efficiency of carbon products of the Cu₂O/Cu electrode reaches 84% at −0.7 V vs. RHE with good selectivity for HCOOH and CO. The current density of Cu₂O/Cu electrode reaches −12.21 mA cm⁻² at −0.8 V vs. RHE, which is much higher than that of the Cu foil electrode (−0.09 mA cm⁻²). In-situ Raman characterization shows that Cu⁺ in Cu₂O/Cu electrode could inhibit hydrogen generation and promote ECO₂RR by stabilizing the adsorption of CO₂.

Electrochemical CO₂ reduction reaction (CO₂RR) exhibits remarkable potential in producing valuable chemicals with renewable energy. Operating CO₂RR in acidic media is beneficial to solve the issue of low carbon utilization brought by (bi)carbonate formation at the cathode. Suppressing the competing hydrogen evolution reaction and achieving stable CO₂RR performance remains challenging. Herein, we constructed a 3-dimensional Cu (3D-Cu) gas diffusion electrode (GDE) to achieve efficient C₂H₄ production with a partial current density (j_C2H4) of over 470 mA cm⁻² and a Faradaic efficiency (FE_C2H4) of 40%. With pause electrolysis, the decay rate of the j_C2H4 is only half that of the traditional constant electrolysis. The GDE after constant electrolysis was found to suffer from severe salt formation, leading to the decreased activity and poor stability.

Electrocatalytic carbon dioxide reduction reaction (CO₂RR) is a promising method to solve current environment and energy issues. Copper-based catalysts have been widely studied for converting CO₂ into value-added hydrocarbon products. Cu monometallic catalyst has been proved to have some shortcomings, including relatively high energy barriers and diverse reaction pathways, leading to low reaction activities and poor product selectivity, respectively. Recently copper-based bimetallic tandem catalysts have attracted extensive attentions due to their special catalyst structure, which can be easily regulated to achieve high CO₂RR reactivity and product selectivity. With the development of quantum chemistry calculations and spectroscopic characterization methods, deep understandings of CO₂RR from the mechanism perspective provide a broad horizon for the design of efficient catalysts. This review offers a good summary of reaction mechanisms and product regulation strategies over copper-based bimetallic catalysts, along with a brief discussion on future directions towards their practical applications.

Electrocatalytic CO₂ reduction reaction (eCO₂RR) has significant relevance to settle the global energy crisis and abnormal climate problem via mitigating the excess emission of waste CO₂ and producing high-value-added chemicals. Currently, eCO₂RR to formic acid or formate is one of the most technologically and economically viable approaches to realize high-efficiency CO₂ utilization, and the development of efficient electrocatalysts is very urgent to achieve efficient and stable catalytic performance. In this review, the recent advances for two-dimensional bismuth-based nanosheets (2D Bi-based NSs) electrocatalysts are concluded from both theoretical and experimental perspectives. Firstly, the preparation strategies of 2D Bi-based NSs in aspects to precisely control the thickness and uniformity are summarized. In addition, the electronic regulation strategies of 2D Bi-based NSs are highlighted to gain insight into the effects of the structure-property relationship on facilitating CO₂ activation, improving product selectivity, and optimizing carrier transport dynamics. Finally, the considerable challenges and opportunities of 2D Bi-based NSs are discussed to lighten new directions for future research of eCO₂RR.

The electrocatalytic CO₂ reduction in aqueous solution mainly involves bond cleavage and formation between C, H and O, and it is highly desirable to expand the bond formation reaction of C with other atoms to obtain novel and valuable chemicals. The electrochemical synthesis of N-containing organic chemicals in electrocatalytic CO₂ reduction via introducing N sources is an effective strategy to expand the product scope, since chemicals containing C–N bonds (e.g. amides and amines) are important reactants/products for medicine, agriculture and industry. This article focuses on the research progress of C–N coupling from CO₂ and inorganic nitrogenous species in aqueous solution. Firstly, the reaction pathways related to the reaction intermediates for urea, formamide, acetamide, methylamine and ethylamine are highlighted. Then, the electrocatalytic performance of different catalysts for these several N-containing products are summarized and classified. Finally, the challenges and opportunities are analyzed, aiming to provide general insights into future research directions for electrocatalytic C–N coupling.

CO₂ electroreduction (CO₂ER) to high value-added chemicals is considered as a promising technology to achieve sustainable carbon neutralization. By virtue of the progressive research in recent years aiming at design and understanding of catalytic materials and electrolyte systems, the CO₂ER performance (such as current density, selectivity, stability, CO₂ conversion, etc.) has been continually increased. Unfortunately, there has been relatively little attention paid to the large-scale CO₂ electrolyzers, which stand just as one obstacle, alongside series-parallel integration, challenging the practical application of this infant technology. In this review, the latest progress on the structures of low-temperature CO₂ electrolyzers and scale-up studies was systematically overviewed. The influence of the CO₂ electrolyzer configurations, such as the flow channel design, gas diffusion electrode (GDE) and ion exchange membrane (IEM), on the CO₂ER performance was further discussed. The review could provide inspiration for the design of large-scale CO₂ electrolyzers so as to accelerate the industrial application of CO₂ER technology.

Electroreduction of carbon dioxide (CO₂) into value-added chemicals offers an entrancing approach to maintaining the global carbon cycle and eliminating environmental threats. A key obstacle to achieving long-term and large-scale implementation of electrochemical CO₂ reduction technology is the lack of active and selective catalysts. Copper (Cu) is one of the few candidates that can facilitate C–C coupling to obtain high-energy oxygenates and hydrocarbons beyond carbon monoxide (CO), but it suffers from poor selectivity for products of interest and high overpotentials. Alloying is an effective way to break the linear scaling relations and uniquely manipulate the reactivity and selectivity, which is hard to achieve by using monometallic compositions alone. By alloying Cu with other metals, one could change the catalytic properties of the catalyst by tuning the local electronic structure and modulating the adsorption strength of the reaction intermediates, thus improving the catalytic activity and selectivity. In this review, we focus on the recently developed Cu-based alloy catalysts (including conventional alloys, high-entropy alloys and single-atom alloys) that have been applied in electrocatalytic CO₂ reduction (ECR). Theoretical calculations and experimental advances in understanding the key rate-limiting and selectivity-determining steps in those alloys are summarized, with a particular focus on identifying binding energy descriptors and the dynamic product formation mechanisms. In addition, we outline the opportunities and challenges in the fundamental understanding of ECR by recommending advanced in-situ characterization techniques and standardized electrochemical methods and offer atomic-level design principles for steering the reaction pathways to the desired products.

Electrocatalytic conversion of carbon dioxide to high value-added chemicals is a promising method for solving the energy crisis and global warming. Electrochemical active metal-containing conjugated polymers have been widely studied for heterogeneous carbon dioxide reduction. In the present contribution, we designed and synthesized a stable cobalt phthalocyanine-based conjugated polymer, named CoPPc-TFPPy-CP, and also explored its electrocatalytic application in carbon dioxide reduction to liquid products in an aqueous solution. In the catalyst, cobalt phthalocyanine acts as building blocks connected with 1,3,6,8-tetrakis(4-formyl phenyl)pyrenes via imine-linkages, leading to mesoporous formation polymers with the pore size centered at 4.1 nm. And the central cobalt atoms shifted to a higher oxidation state after condensation. With these chemical and structural natures, the catalyst displayed a remarkable electrocatalytic CO₂ reduction performance with an ethanol Faradaic efficiency of 43.25% at −1.0 V vs RHE. While at the same time, the electrochemical reduction process catalyzed by cobalt phthalocyanine produced only carbon monoxide and hydrogen. To the best of our knowledge, CoPPc-TFPPy-CP is the first example among organic polymers and metal-organic frameworks that produces ethanol from CO₂ with a remarkable selectivity.

The solid oxide electrolytic cell (SOEC) is one of the most promising energy conversion and storage devices, which could convert CO₂ to CO with high Faradaic efficiency and production rate. However, the lack of active and stable cathode materials impedes their practical applications. Here we focus on the promising perovskite oxide cathode material Sr₂Fe_1.5Mo_0.5O_6−σ, with the aim of understanding how A-atom stoichiometry and catalytic performance are linked. We find that increasing the strontium content in the perovskite improves the chemisorption of CO₂ on its surface, forming a SrCO₃ phase. This hinders the charge transfer and oxygen exchange processes. Simultaneously, strontoium segregation to the cathode surface facilitates coking of the surface during CO₂ electrolysis, which poisons the electrode. Consequently, a small number of Sr deficiencies are optimal for both electrochemical performance and long-term stability. Our results provide new insights for designing high-performance CO₂ electrolysis cathode materials.