Thermal-Driven Dispersion of Bismuth Nanoparticles among Carbon Matrix for Efficient Carbon Dioxide Reduction.

The poor electrocatalytic stability and rapid deactivation of metal electrocatalysts are always present in the electrocatalytic conversion of carbon dioxide (CO2) due to the harsh reduction condition. Herein, we demonstrate the controllable dispersion of ultrafine bismuth nanoparticles among the hollow carbon shell (Bi@C-700-4) simply by a thermal-driven diffusion process. The confinement effect of nitrogen-doped carbon matrix is able to low the surface energy of bismuth nanoparticles against the easy aggregation commonly observed for the thermal treatment. On the basis of the synergistic effect and confinement effect between bismuth nanoparticles and carbon matrix, the highly dispersed active sites render the obviously improved electrocatalytic activity and stability for CO2 reduction into formate. The in situ experimental observations on the reduction process and theoretical calculations reveal that the incorporation of bismuth nanoparticles with nitrogen-doped carbon matrix would promote the activation of CO2 and the easy formation of key intermediate (*OCHO), thus leading the enhanced electrocatalytic activity, with a Faradaic Efficiency (FE) of formate about 94.8 % and the long-time stability. Furthermore, the coupling of an anode for 5-hydroxymethylfurfural oxidation reaction (HMFOR) in solar-driven system renders the high 2,5-furandicarboxylic acid (FDCA) yield of 81.2 %, presenting the impressive solar-to-fuel conversion.

Atomic bismuth induced ensemble sites with indium towards highly efficient and stable electrocatalytic reduction of carbon dioxide.

Structural reconstruction is commonly observed during electrocatalytic CO2 reduction (CO2RR) process. However, the proper modulation of interface and defect sites remains challenging with the mechanism understanding to realize the favorable electrocatalysis. Herein, the atomic bridging of bismuth with indium atoms is elaborately designed for improving electrocatalysis of CO2RR via electrochemical reduction and in situ anchoring strategy. As revealed by in situ structure analysis and theoretical studies, the ensemble sites supported on carbon matrix enable the charge density gradient to significantly promote the adsorption of *OCHO intermediate by the regulation of σ bonding and π* back-donation. Consequently, such unique electrocatalyst achieves the high formate faradaic efficiency of 95.1% over the entire potential range tested and the long-lived stability for 9 d. With coupling of CO2RR, the solar-driven full cell demonstrates the spontaneous production of formate and 2,5-furandicarboxylic acid via the efficient oxidation of 5-hydroxymethylfurfural with an outstanding yield of 88.2%, highlighting the impressive solar-to-fuel conversion selectivity. Monitoring and understanding the intrinsic active sites of biatomic bridge are crucial to elucidate the synergic electrocatalysis for rationally designing high-performance electrocatalysts.

Performance and mechanism of Pb2+ and Cd2+ ions' adsorption via modified antibiotic residue-based hydrochar.

This study investigated the hydrochar-based porous carbon prepared by combining the technical route of hydrothermal carbonization (HTC) + chemical activation. The hydrochar morphology was adjusted by changing the activation reaction conditions and adding metal salts. Experiments showed that the activation of KHCO3 significantly increased the specific surface area and pore size of the hydrochar. Besides, oxygen-rich groups on the surface of the activated hydrochar interacted with heavy metal ions to achieve efficient adsorption. The activated hydrothermal carbon adsorption capacity for Pb2+ and Cd2+ ions reached 289 and 186 mg/g, respectively. The adsorption mechanism study indicated that the adsorption of Pb2+ and Cd2+ was related to electrostatic attraction, ion exchange, and complexation reactions. The "HTC + chemical activation" technology was environmentally friendly and effectively implemented antibiotic residues. Carbon materials with high adsorption capacity can be prepared so that biomass resources can be utilized with excessive value, as a consequence presenting technical assistance for the comprehensive disposal of organic waste in the pharmaceutical industry and establishing a green and clean production system.

Interface Molecular Functionalization of Cu2O for Synchronous Electrocatalytic Generation of Formate.

The electrocatalytic generation of valuable fuels and chemicals from carbon dioxide (CO2) and others with the assistance of clean solar energy is a highly promising way to realize the carbon-neutral cycle, which invokes the systematic development of advanced electrocatalysts for efficient and selective redox reactions of feedstocks. Herein, we demonstrate the interface modification of cuprous oxide with polyvinylpyrrolidone (PVP) to improve the electrocatalytic efficiency for the synchronous formate generation. Density functional theory calculations reveal that the interfacial properties can be effectively regulated by the PVP functionalization for the favorable formation of intermediates to improve the selectivity of formate generation. Importantly, the advanced electrocatalyts enable an efficient coupling of CO2 reduction with methanol oxidation in an electrochemical cell powered with a solar cell. The work provides a predictive link between the electrocatalytic redox reactions by applying the interfacial regulation strategies of electrocatalysts.

Atomic Bridging Structure of Nickel-Nitrogen-Carbon for Highly Efficient Electrocatalytic Reduction of CO2.

To meet strategic applications, electrochemical reduction of CO2 into value-added chemical molecules would be improved by the rational design of advanced electrocatalysts with atomically dispersed active sites. Herein an electrospun-pyrolysis cooperative strategy is presented to not only modulate the porous structure of the carbon support for favorable charge and mass transfer, but also adjust the bridging structure of atomically dispersed metal species. Typically, the experimental results and theoretical calculations revealed that the unique chemical structure of binuclear nickel bridging with nitrogen and carbon atoms (namely Ni2 -N4 -C2 ) tunes the electronic nature of the d-states for the optimal adsorption of carbon dioxide and intermediates, thus inducing the substantial enhancement of CO2 reduction via the thermodynamically more favorable pathway. The identification of such a structure demonstrates the large space to modulate the atomic bridging status for optimizing electrocatalysis.

In Situ Characterization for Boosting Electrocatalytic Carbon Dioxide Reduction.

The electrocatalytic reduction of carbon dioxide into organic fuels and feedstocks is a fascinating method to implement the sustainable carbon cycle. Thus, a rational design of advanced electrocatalysts and a deep understanding of reaction mechanisms are crucial for the complex reactions of carbon dioxide reduction with multiple electron transfer. In situ and operando techniques with real-time monitoring are important to obtain deep insight into the electrocatalytic reaction to reveal the dynamic evolution of electrocatalysts' structure and composition under experimental conditions. In this paper, the reaction pathways for the CO2 reduction reaction (CO2 RR) in the generation of various products (e.g., C1 and C2 ) via the proposed mechanisms are introduced. Moreover, recent advances in the development and applications of in situ and operando characterization techniques, from the basic working principles and in situ cell structure to detailed applications are discussed. Suggestions and future directions of in situ/operando analysis are also addressed.

Anchoring and Upgrading Ultrafine NiPd on Room-Temperature-Synthesized Bifunctional NH2 -N-rGO toward Low-Cost and Highly Efficient Catalysts for Selective Formic Acid Dehydrogenation.

Hydrogen is widely considered to be a sustainable and clean energy alternative to the use of fossil fuels in the future. Its high hydrogen content, nontoxicity, and liquid state at room temperature make formic acid a promising hydrogen carrier. Designing highly efficient and low-cost heterogeneous catalysts is a major challenge for realizing the practical application of formic acid in the fuel-cell-based hydrogen economy. Herein, a simple but effective and rapid strategy is proposed, which demonstrates the synthesis of NiPd bimetallic ultrafine particles (UPs) supported on NH2 -functionalized and N-doped reduced graphene oxide (NH2 -N-rGO) at room temperature. The introduction of the NH2 N group to rGO is the key reason for the formation of the ultrafine and well-dispersed Ni0.4 Pd0.6 UPs (1.8 nm) with relatively large surface area and more active sites. Surprisingly, the as-prepared low-cost NiPd/NH2 -N-rGO dsiplays excellent hydrophilicity, 100% H2 selectivity, 100% conversion, and remarkable catalytic activity (up to 954.3 mol H2 (mol catalyst)-1 h-1 ) for FA decomposition at room temperature even with no additive, which is much higher than that of the best catalysts so far reported.

Amorphizing of Au Nanoparticles by CeOx -RGO Hybrid Support towards Highly Efficient Electrocatalyst for N2 Reduction under Ambient Conditions.

Ammonia synthesis is one of the most kinetically complex and energetically challenging chemical processes in industry and has used the Harber-Bosch catalyst for over a century, which is processed under both harsh pressure (150-350 atm) and hightemperature (623-823 K), wherein the energy and capital intensive Harber-Bosch process has a huge energy cost accounting for about 1%-3% of human's energy consumption. Therefore, there has been a rough and vigorous exploration to find an environmentally benign alternative process. As the amorphous material is in a metastable state and has many "dangling bonds", it is more active than the crystallized one. In this paper, CeOx -induced amorphization of Au nanoparticles anchored on reduced graphite oxide (a-Au/CeOx -RGO) has been achieved by a facile coreduction method under ambient atmosphere. As a proof-of-concept experiment, a-Au/CeOx -RGO hybrid catalyst containing the low noble metal (Au loading is 1.31 wt%) achieves a high Faradaic efficiency (10.10%) and ammonia yield (8.3 µg h-1 mg-1cat. ) at -0.2 V versus RHE, which is significantly higher than that of the crystalline counterpart (c-Au/RGO), and even comparable to the yields and efficiencies under harsh temperatures and/or pressures.

Au Sub-Nanoclusters on TiO2 toward Highly Efficient and Selective Electrocatalyst for N2 Conversion to NH3 at Ambient Conditions.

As the NN bond in N2 is one of the strongest bonds in chemistry, the fixation of N2 to ammonia is a kinetically complex and energetically challenging reaction and, up to now, its synthesis is still heavily relying on energy and capital intensive Haber-Bosch process (150-350 atm, 350-550 °C), wherein the input of H2 and energy are largely derived from fossil fuels and thus result in large amount of CO2 emission. In this paper, it is demonstrated that by using Au sub-nanoclusters (≈0.5 nm ) embedded on TiO2 (Au loading is 1.542 wt%), the electrocatalytic N2 reduction reaction (NRR) is indeed possible at ambient condition. Unexpectedly, NRR with very high and stable production yield (NH3 : 21.4 µg h-1 mg-1cat. , Faradaic efficiency: 8.11%) and good selectivity is achieved at -0.2 V versus RHE, which is much higher than that of the best results for N2 fixation under ambient conditions, and even comparable to the yield and activation energy under high temperatures and/or pressures. As isolated precious metal active centers dispersed onto oxide supports provide a well-defined system, the special structure of atomic Au cluster would promote other important reactions besides NRR for water splitting, fuel cells, and other electrochemical devices.