Electrocatalytic Reduction of Carbon Dioxide to Methane on Single Transition Metal Atoms Supported on a Defective Boron Nitride Monolayer: First Principle Study

The electrochemical conversion of carbon dioxide (CO2) and water into useful multi‐electron transfer products, such as methanol (CH3OH) and methane (CH4), is a major challenge in facilitating a closed carbon cycle. Here, a systematic first principle study of the potential of single transition metal atoms (Sc to Zn, Mo, Rh, Ru, Pd, Ag, Pt, and Au) supported on experimentally available defective boron nitride monolayers with a boron monovacancy (TM/defective BN) to achieve highly efficient electrocatalytic CO2 reduction (ECR) to CH4 is carried out. Our computations reveal that Fe/defective BN, Co/defective BN, and Pt/defective BN nanosheets possess outstanding ECR activities with quite low (less negative) onset potentials of −0.52, −0.68, and −0.60 V, respectively. Given that Fe and Co are nonprecious metals, Fe/defective BN and Co/defective BN may provide cost‐effective electrocatalysts. The high ECR activities of these TM/defective BN catalyst systems stem from the moderate electrocatalysts’ affinities for C and O, which modulate the free energies of ECR intermediates in the reaction pathways. Moreover, it is found that Fe/defective BN and Pt/defective BN show high selectivity of ECR to CH4. This finding highlights a strategy to design highly active and selective single‐atom electrocatalysts for ECR to CH4.S.S. and H.A. acknowledge the financial support by the Australian Research Council under Discovery Project (DP170104853). This research was undertaken with the assistance of resources provided by the National Computing Infrastructure facility at the Australian National University, allocated through both the National Computational Merit Allocation Scheme supported by the Australian Government and the Australian Research Council grant LE120100181 (Enhanced merit-based access and support at the new NCI petascale supercomputing facility, 2012–2015)

Impact of surface defects on LaNiO3 perovskite electrocatalysts for the oxygen evolution reaction

Perovskite oxides are regarded as promising electrocatalysts for water splitting due to their cost-effectiveness, high efficiency and durability in the oxygen evolution reaction (OER). Despite these advantages, a fundamental understanding of how critical structural parameters of perovskite electrocatalysts influence their activity and stability is lacking. Here, we investigate the impact of structural defects on OER performance for representative LaNiO3 perovskite electrocatalysts. Hydrogen reduction of 700¿°C calcined LaNiO3 induces a high density of surface oxygen vacancies, and confers significantly enhanced OER activity and stability compared to unreduced LaNiO3; the former exhibit a low onset overpotential of 380 mV at 10 mA¿cm-2 and a small Tafel slope of 70.8 mV¿dec-1. Oxygen vacancy formation is accompanied by mixed Ni2+/Ni3+ valence states, which quantum-chemical DFT calculations reveal modify the perovskite electronic structure. Further, it reveals that the formation of oxygen vacancies is thermodynamically more favourable on the surface than in the bulk; it increases the electronic conductivity of reduced LaNiO3 in accordance with the enhanced OER activity that is observed.Peer ReviewedPostprint (author's final draft

Ethanol Dehydration over Silica-Supported H₁PW₁₂O₄₀and the Role of Water

Catalytic dehydration of (bioderived) ethanol to ethylene or diethyl ether (DEE) offers an atom-efficient route to commodity chemicals and renewable aviation fuels. Here, the impact of silica support morphology and dispersion of H3PW12O40 (HPW) on the vapor-phase dehydration of ethanol to ethylene and DEE was investigated. Ethanol conversion at 175 °C and ambient pressure was inversely proportional to HPW dispersion over a fumed silica and mesoporous SBA-15 support, with specific activity directly proportional to the crystalline water content, highlighting the importance of catalysis within the pseudo-liquid phase. A common turnover frequency of ∼2500 h–1 was determined for HPW/SBA-15, with all acid sites participating. Catalyst deactivation at 175 °C could be suppressed by co-feeding 10 wt % water, likely by mitigating the loss of crystalline (acidic) water; higher reaction temperatures induce decomposition of the heteropolyanion to WO3 and could also be partially suppressed by co-fed water. In the presence of co-fed water, the optimum 50 wt % HPW/SBA-15 catalyst could be used for three consecutive reactions at 175 °C with minimal loss of activity or selectivity without any reactivation protocol. Ethanol dehydration was selective to DEE (∼80%) for reaction <225 °C, with higher temperatures inducing a switchover to ethylene (87% ≥ 300 °C) in accordance with thermodynamic predictions. Maximum steady-state DEE productivity was 600 mmol·gcat–1·h–1 at 175 °C, and maximum steady-state ethylene productivity was 1800 mmol·gcat–1·h–1 at 225 °C. In situ DRIFTS identified the protonated ethanol dimer (C2H5OH)2H+ as the reactive intermediate to DEE formation, with higher temperatures favoring the formation of protonated ethanol (C2H5OH)H+ and ethoxy intermediates to ethylene

Advances in reforming and partial oxidation of hydrocarbons for hydrogen production and fuel cell applications

One of the most attractive routes for the production of hydrogen or syngas for use in fuel cell applications is the reforming and partial oxidation of hydrocarbons. The use of hydrocarbons in high temperature fuel cells is achieved through either external or internal reforming. Reforming and partial oxidation catalysis to convert hydrocarbons to hydrogen rich syngas plays an important role in fuel processing technology. The current research in the area of reforming and partial oxidation of methane, methanol and ethanol includes catalysts for reforming and oxidation, methods of catalyst synthesis, and the effective utilization of fuel for both external and internal reforming processes. In this paper the recent progress in these areas of research is reviewed along with the reforming of liquid hydrocarbons, from this an overview of the current best performing catalysts for the reforming and partial oxidizing of hydrocarbons for hydrogen production is summarized

Stability of unstable perovskites : recent strategies for making stable perovskite solar cells

Perovskite solar cells (PSCs) are now crossing the certified 23.2% power conversion efficiency (PCE), however, the stability of organic-lead halide perovskites, cost of additives doped hole transport layer (HTL) and upscaling from lab-scale to industrial scale without hampering its efficiency are challenging tasks for its commercial application. These problems could be tackled via different aspects which includes the synthesis of promising electron transport layers (ETLs) and HTLs, synthesis of mixed perovskites via combination of 3D and stable 2D perovskite, replacement of poor-stable methylammonium (MA) cation with MA free perovskite and capping inorganic materials will be the best choice toward highly efficient air-thermal-stable perovskite solar cells (PSCs). This perspective focuses on the current strategies in PSCs for making the stable PSCs via low-cost, easily processed components and shared our views toward commercialization

Catalytic reduction of nitrogen to produce ammonia by bismuth-based catalysts: state of the art and future prospects

This review provides an up-to-date review on Bi-based nitrogen-fixation materials and future directions for the development of new Bi-based nitrogen-fixation materials under ambient conditions.</p

九州におけるソバ遺伝資源の諸特性の品種間差異および機能性の選抜法に関する研究

博士（農学）神戸大

Orientation Growth and Magnetic Properties of Electrochemical Deposited Nickel Nanowire Arrays

Highly ordered ferromagnetic metal nanowire arrays with preferred growth direction show potential applications in electronic and spintronic devices. In this work, by employing a porous anodic aluminum oxide template-assisted electrodeposition method, we successfully prepared Ni nanowire arrays. Importantly, the growth direction of Ni nanowire arrays can be controlled by varying the current densities. The crystalline and growth orientation of Ni nanowire arrays show effects on magnetic properties. Single-crystallinity Ni nanowires with [110] orientation show the best magnetic properties, including coercivity and squareness, along the parallel direction of the nanowire axis. The current preparation strategy can be used to obtain other nanowire arrays (such as metal, alloy, and semiconductor) with controlled growth direction in confined space, and is therefore of broad interest for different applications

A Green Synthesis of Ru Modified g-C3N4 Nanosheets for Enhanced Photocatalytic Ammonia Synthesis

Nitrate is a crucial environmental pollutant, and its risk on ecosystem keeps increasing. Photocatalytic conversion of nitrate to ammonia can simultaneously achieve the commercialization of environmental hazards and recovery of valuable ammonia, which is green and sustainable for the planet. However, due to the thermodynamic and kinetic energy barriers, photocatalytic nitrate reduction usually involves a higher selectivity of the formation of nitrogen that largely limits the ammonia synthesis activity. In this work, we reported a green and facile synthesis of novel metallic ruthenium particle modified graphitic carbon nitride photocatalysts. Compare with bulk graphitic carbon nitride, the optimal sample had 2.93-fold photocatalytic nitrate reduction to ammonia activity (2.627 mg/h/gcat), and the NH3 selectivity increased from 50.77% to 77.9%. According to the experimental and calculated results, the enhanced photocatalytic performance is attributed to the stronger light absorption, nitrate adsorption, and lower energy barrier for the generation of ammonia. This work may provide a facile way to prepare metal modified photocatalysts to achieve highly efficient nitrate reduction to ammonia