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Urea is of great importance for the survival and development of mankind because of its advantages in effectively increasing crop yields. A novel carbon-supported indium-doped bismuth nanoparticles (Bi: 10 %In/C NPs) was prepared for the synthesis of urea via the co-activated reduction of nitrate and CO 2 with an average Faraday efficiency (FE) of 20.31 % and urea yield (R urea) of 606.38 μg mg−1 h−1. Interestingly, the In doped here not only serves as the active site, but also acts as an activator to stimulate the activity of Bi through electronic interaction, thus making Bi also the active site for the electrocatalytic C-N coupling reaction. Simultaneously, the key intermediates of the reaction are revealed to be *NH 2 and *CO. This work provides further insight into the role of indium in the electrocatalytic C-N coupling for the synthesis of urea, which gives a direction for thinking about the design and construction of subsequent highly efficient electrocatalysts. A novel catalyst based on carbon-supported In-doped Bi nanoparticles (Bi:10 % In/C NPs) was prepared for the co-activated reduction of nitrate and CO 2 for the synthesis of urea with average FE and urea yield of 20.31 % and 606.38 μg mg−1 h−1 at − 0.45 V vs. RHE. The key intermediates of the reaction are revealed to be *NH 2 and *CO. Interestingly, experimental results show that the doped In acts not only as the active site but also as an "activator", stimulating the activity of Bi through electronic interactions, thus making Bi also the active site for electrocatalytic C-N coupling reactions. [Display omitted] ● A bismuth-based catalyst well suited for the electrochemical synthesis of urea (FE: 20.31 %, R urea : 606.38 μg mg−1 h−1) was prepared by a simple room temperature reduction method based on the property of bismuth to inhibit competitive hydrogen evolution reactions. ● A strategy for the preparation of electrocatalysts for highly efficient urea synthesis using direct activation of bismuth by indium is proposed for the first time. ● Theindium in the prepared Bi:In/C not only directly participates in the synthesis of urea as the active site, but also acts as an activator to activate the inert bismuth, so that bismuth also becomes the active site of the C-N coupling reaction, thus greatly improving the efficiency and stability for the synthesis of urea. [ABSTRACT FROM AUTHOR]

This paper describes the effects of defect distribution on energy band structure and the subsequent photocatalytic activity over TiO 2 with exposed {001} facets as the model catalyst. Our results show that only surface oxygen vacancies (V o ’s) and Ti 3+ centers in TiO 2 can be induced by hydrogenation treatment, whereas the generation of bulk V o ’s and Ti 3+ species depends on the thermal treatment in nitrogen. Both the surface and bulk defects in TiO 2 can promote the separation of electron-hole pairs, enhance the light absorption, and increase the donor density. The presence of surface and bulk defects in TiO 2 can not change the valence band maximum, but determine the conduction band minimum. Surface defects in TiO 2 induce a tail of conduction band located above the H + /H 2 redox potential, which benefits the photocatalytic performance. However, bulk defects in TiO 2 generate a band tail below the H + /H 2 potential, which inhibits hydrogen production. Thus, the change of band gap structure by defects is the major factor to determine the photocatalytic activity of TiO 2 for hydrogen evolution. It is a new insight into the rational design and controllable synthesis of defect-engineered materials for various catalytic processes. [ABSTRACT FROM AUTHOR]

Development of efficient electrocatalysts requires construction of catalytic surfaces with moderate H adsorption energy. Here, we address this challenge by Br-induced formation of P-poor defective nickel phosphide and show that the H adsorption energy can be optimized by regulating the vacancy concentration. We show that when such defective Ni 12 P 5−x Br x nanoparticles are distributed on the surface of Ni 2 P nanosheets (Ni 12 P 5−x Br x /Ni 2 P NS), excellent catalytic activity for water splitting is obtained in alkaline media. Density functional theory computations revealed that Br doping induce the formation of a P-poor nickel phosphide with vacancies, leading to an optimal H adsorption strength with a volcano-type relationship. This is the best reported for a non-precious metal phosphide at present: the overpotential for HER is 18 mV at 10 mA cm−2 and 155 mV for OER. This leads to an exceptionally low cell voltage requirement of only 1.44 V to drive overall water splitting in an alkaline electrolyzer. [Display omitted] • Br-induced nickel phosphide formation energy change achieves P-poor defective phase configuration. • Multi-level regulation of vacancy content, morphology and catalytic performance by temperature is achieved. • DFT calculations show that Ni 12 P 5−x Br x shows a volcano-type relationship related to vacancy content. [ABSTRACT FROM AUTHOR]

Efficiency of the electrocatalysts for hydrogen evolution reaction (HER) strongly depends on their extrinsic physical properties and intrinsic electronic structures. Among various modulation strategies, nanoalloying is an efficient route to regulate the intrinsic activities of HER intermediates. Herein, we develop a facile and universal one-step pyrolyzed method to fabricate bimetallic Ru-based nanoalloy catalysts encapsulated by B/N co-doped graphitic nanotubes (RuM@BCN, M=Ir, Pt, Ag, Co, and Fe) for high-performance alkaline HER. BCN nanotube substrates provide sufficient open channels, porous structures and strong anchoring effect to achieve fast kinetics and high stability. The bimetallic nanoalloying strategy greatly promotes the water dissociation and hydrogen adsorption ability of the electrocatalysts via modulation on their intrinsic electronic structures. Therefore, the as-made RuM@BCN demonstrates varied HER behaviors by alloying metals, in which RuIr@BCN exhibits the highest alkaline HER activity with an overpotential of 23.6 mV at the current density of 10 mA cm−2, outperforming commercial Pt/C. [Display omitted] • A general and facile strategy is developed to fabricate bimetallic RuM@BCN nanotubes. • Alloying Ru and Ir atoms induces electronic structure changes and promotes alkaline HER. • BCN nanotubes show great potentials to embed various Ru-based nanoalloy catalysts. • RuIr@BCN demonstrates an overpotential of 23.6 mV at 10 mA cm− 2 for alkaline HER. [ABSTRACT FROM AUTHOR]

Tandem Catalysis on dual active sites A highly-efficient electrocatalyst containing dual active sites of Fe-NiOOH and NiC 4 single atoms was synthesized, and a tandem catalysis mechanism of OER on dual active sites was proposed to reveal the high-activity origin of the catalysts. This work provides a new concept of tandem catalysis to develop the electrocatalysts with many elementary steps, like OER and ORR. [Display omitted] • A highly-efficient electrocatalyst containing dual active sites of Fe-NiOOH and NiC 4 single atoms was synthesized. • The dual active site electrocatalyst shows obviously better OER performance than the corresponding single active site one. • A tandem catalysis mechanism was proposed to reveal the synergistic catalysis of two active centers. • This work provides a new concept of tandem catalysis to develop the electrocatalysts with many elementary steps, like OER and ORR The high voltage in oxygen evolution reaction (OER) often causes structural change in electrocatalysts and forms multiple active sites. Therefore, exploring the synergy of various active sites is extremely significant to develop catalysts for OER with multiple elementary steps. Herein, we adopt the physically adsorbed metal ions method to successfully synthesize a highly-efficient electrocatalyst containing the dual active sites of Fe-NiOOH and NiC 4 single atoms (marked as Ni SAs/Fe-NiOOH). The Ni SAs/Fe-NiOOH displays outstanding OER performance with an overpotential of 269 mV to deliver current density of 10 mA/cm2 that shows 55 mV superior to commercial IrO 2 /CB at the same condition. Experiments and density functional theory calculations indicate that the excellent OER activity of Ni SAs/Fe-NiOOH catalyst is attributed to the synergy of dual active sites of NiC 4 SAs and Fe-NiOOH. A tandem catalysis mechanism is also proposed to reveal the synergism of two active centers, which makes the potential-determining step more facile and accordingly decreases the OER overpotential. This work offers a new concept of tandem catalysis to develop the electrocatalysts with many elemental steps, like OER and oxygen reduction reaction catalysts. [ABSTRACT FROM AUTHOR]

A novel structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) composed of defect-rich NiO phase and Ni clusters anchored on outside of nanotubes is presented. The d-band downshifted by Fe-doping, coupled of Ni clusters and defect-rich nature greatly improve electrocatalytic performances of Fe-NiO-Ni CHNAs toward oxygen evolution reaction. • A multi-level structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) was synthesized as a catalyst for OER. • Fe-NiO-Ni CHNAs exhibits overpotential of 245 mV at 10 mA cm−2 and outstanding durability that surpasses most of transition metal oxides. • The improved OER activity is mainly because Fe doping downshifts the d-band of metal sites. • Fe-NiO-Ni CHNAs obeyed the adsorbate evolution mechanism with a nonconcerted proton-electron transfer pathway. Herein we present a novel multi-level structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) grown on carbon fiber cloth as an efficient catalyst for oxygen evolution reaction. In this multi-level structure, rocksalt-type Fe-doped NiO phase hybrids with Ni clusters coupled into the nanospheres anchored to the outside of nanotube, forming a unique 3D corn-like structure. This novel multi-level structure represents a large specific area for catalytic reaction. X-ray absorption fine structure indicates that the defect-rich Fe-doped NiO phase has abundant coordinative unsaturated sites as active sites, and Fe doping downshifts the d-band of metal sites, which is the main contribution to the improved oxygen evolution reaction catalytic activity. The OER of Fe-NiO-Ni CHNAs obeys the adsorbate evolution mechanism with the nonconcerted proton-electron transfer pathway as a rate-determining step. Thus Fe-doped NiO CHNAs exhibits excellent OER performance and outstanding durability that surpasses most of transition metal oxides. [ABSTRACT FROM AUTHOR]

Asymmetric Embedding Benzene Ring in graphite carbon nitride changes local charge distribution and electron transfer kinetics, and promote the photocatalytic water splitting to produce hydrogen at a higher rate. • The A-GCN is successfully prepared using dicyandiamide and terephthalonitrile. • Embedding benzene regulate the localized electronic structure. • Theoretical results predicts the localized asymmetry promotes the charge transfer. • For hydrogen production, the A-GCN-1.0 displays 10.8 times as good as pristine GCN. Preventing the high carrier recombination rate of graphitized C 3 N 4 (GCN) is an urgent problem to be solved for its application as a photocatalyst for hydrogen production. Here, we first rationally embed the benzene ring in GCN to modify the local symmetry without changing its long-order structure. Theoretical calculation predicts that this design can change the electronic structure and promote the effective charge transfer in GCN. The benzene ring embedded GCN is successfully prepared by copolymerization using dicyandiamide and terephthalonitrile as precursors. Photoluminescence (PL) and time-resolved transient PL (TRPL) spectra confirm that the electron transfer efficiency of the benzene ring embed GCN is greatly improved. This nanomaterial displays 10.8 times higher photocatalytic hydrogen production rate than that of pristine GCN with the apparent quantum yield of 11.3% at 400 nm and 9% at 420 nm. This work provides a novel strategy for designing high-efficiency two-dimensional (2D) photocatalytic materials for water splitting. [ABSTRACT FROM AUTHOR]