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The conventional Haber‐Bosch method for the ammonia synthesis process requires high temperature and pressure. Electrochemical synthesis of ammonia, an emerging ammonia synthesis technology, is a promising approach for sustainable ammonia production that is energy‐efficient and free of greenhouse gas emissions. The design and development of high‐performance catalysts are the keys to promoting the sustainable ammonia production process. This work synthesized a PdCu alloy catalyst loaded on a graphene oxide carrier through a simple liquid phase reduction method. Which greatly enhanced the catalytic performance with an ammonia yield of 1.62 mg h−1cm−2 and Faradaic efficiency of 38.2 % under the nitrate reduction ammonia synthesis (NO3RR) reaction at an overpotential of −0.4 V. For the nitrogen reduction ammonia (NRR), the ammonia yield was 20.83 μg h−1 cm−2 with a Faradaic efficiency of 3.8 %. This study may provide a new idea for material design and promote ammonia synthesis development under ambient conditions. [ABSTRACT FROM AUTHOR]

Fuel cell is an emerging technology for energy conservation and environmental protection, with simple structure and high energy conversion efficiency. However, the kinetics of cathode ORR is slow. Therefore, high-performance, highly selective catalysts are urgently needed. This work aims to use the DFT to conduct structural design and performance optimization of Ni/CNTs and Ni/X-CNTs (X=B, N, O) catalysts. Studies showed that the number of Ni atom loading, the number and types of doping of heteroatoms all affected the activity of catalysts to some extent. The adsorption energy of O2 was calculated to determine that O2 was adsorbed on Ni(6)/B(2)-CNTs in the Bridge mode. Meanwhile, the comparative analysis of 2 e− path and 4 e− path indicated that ORR occurred in Ni(6)/B(2)-CNTs in acidic medium was more inclined to follow the 4 e− path. The present work has some reference and value for specific experiments. [ABSTRACT FROM AUTHOR]

It is of increasing importance to develop highly active and economical oxygen reduction reaction (ORR) electrocatalysts, which have great significance for the large‐scale implementation of various energy conversion systems, including metal–air batteries and fuel cells. Herein, a novel method to synthesize FeNx‐decorated carbon nanotubes as a high‐efficiency ORR catalyst, by utilizing ZnO nanowires as a sacrificial template and a Fe–polydopamine complex as metal and carbon sources, is reported. The obtained catalyst shows great potential for replacing Pt/C as the ORR catalyst under various pH conditions, from alkaline to acidic electrolytes. The high conductivity, large surface area of the carbon nanotube, and highly active FeNx species contributed greatly to the high performance of the catalyst. The work presented herein paves a new way for the synthesis of 1D porous nanomaterials for a broad range of energy‐related applications. Doped to reduce: FeNx‐decorated carbon nanotubes are prepared by utilizing ZnO nanowires as a sacrificial template and Fe–polydopamine (Fe–PDA) complex as metal and carbon sources (see figure). The evaporation of Zn at high temperature results in a high surface area of the carbon nanotubes, and the FeNx species contribute greatly to the oxygen reduction reaction activity of the catalyst. [ABSTRACT FROM AUTHOR]

Abstract: The oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) are two of the core reactions that occur in fuel cells and water electrolysis devices. Heteroatom-doped carbon materials are promising metal-free electrocatalysts to improve the conversion efficiency of these devices. To optimize the nanostructures of such carbon-based catalysts, herein, we reported an effective template method to synthesize N doped carbon nanotubes by using polydopamine as a precursor. The use of the ZnO nanowire not only serves as a self-sacrificial template to direct the formation of the nanotube, but also greatly extends the porosity of the carbon nanotube. Moreover, the polydopamine precursor also leads to effective N doping. An optimized sample, NCNT-900, shows high ORR performance comparable with that of Pt/C as well as good HER performance in both alkaline and acid media, making it one of the most effective carbon-based HER catalysts. This strategy offers an opportunity to synthesize catalysts with higher activity by rational design of a carbon precursor with higher N content or multi-heteroatom co-doping.Graphical Abstract: Nitrogen doped carbon nanotube with high performance for both ORR and HER was synthesized using ZnO nanowires as template. The obtained materials show effective N doping that provides abundant active sites, high surface area and unique textural parameters that can effectively enhance mass transfer. When used for electrocatalysts, NCNT-900 shows high ORR performance comparable with that of Pt/C and good HER performance in both alkaline and acid media. [ABSTRACT FROM AUTHOR]

One-dimensional MoO2–Co2Mo3O8@C nanorods were synthesized by using MoO3@ZIF-67 composites as a precursor for the first time, and it is found that the Co2Mo3O8 species and its composite have excellent OER activities. The MoO2–Co2Mo3O8@C nanorods present favorable electrocatalytic advantages toward OER in alkaline solution, requiring an overpotential of only 320 mV to deliver a current density of 10 mA cm−2. In addition, the catalyst also shows a small Tafel slope of 88 mV dec−1 and relatively good durability. The attractive OER performance can be attributed to the highly active Co2Mo3O8 and MoO2 species and the unique structure of the catalyst. This strategy can be extended to design and synthesize other novel and highly efficient molybdenum based ternary metal oxides as OER catalysts. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells with sub-5 μm-thick Pt/SiC-P (1.79 at. % Pt), Pt/SiC-M (0.45 at. % Pt), and Pt/SiC-R (0.39 at. % Pt) counter electrode (CE) films fabricated by using three different processes produced power conversion efficiencies of 6.82, 7.64, and 7.04 % that reached 86.5, 97.0, and 89.3 %, respectively, of the level obtained by using a print-Pt CE (7.88 %). These materials can reduce the cost of CEs and solve challenges involving Pt. [ABSTRACT FROM AUTHOR]

TaO‐ and TaC‐based nanocomposites as novel and low‐cost counter electrodes (CEs) in dye‐sensitized solar cells (DSCs) show outstanding electrocatalytic activity and photovoltaic performance, superior to the Pt electrode. Based on the first‐principles density functional theory (DFT) calculations, I3 is chemisorbed onto the TaO surface as opposed to physical adsorption on the TaC surface. The TaO‐based composite is more efficient than the TaC‐based composite as a CE in DSCs. [ABSTRACT FROM AUTHOR]

Synthesized niobium oxides (Nb2O5and NbO2) were applied for the first time as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). The DSC using NbO2CE showed a higher power conversion efficiency of 7.88%, compared with that of the DSC using Pt CE (7.65%). [ABSTRACT FROM AUTHOR]

[Display omitted] • Overview of Cu-based catalysts for ECR with C 2+ products are presented. • In-depth discussion of electrochemical synthesized Cu based catalysts with different types. • Outline of the ordinary methods combined with electrochemical synthesis for Cu based catalysts. • Perspective on the development potential of electrochemical synthesized Cu based catalysts for ECR. In recent decades, catalytic reduction of CO 2 is a hot topic in the research field of electrocatalysis. Copper is the only metal catalyst capable of producing multiple carbon (C 2+) products in electrocatalytic CO 2 reduction (ECR), however, there are still many challenges such as low selectivity, serious hydrogen evolution (HER) and poor stability. So far, various synthesis methods have been developed for Cu-based catalysts. Compared with ordinary chemical synthesis, electrochemical method has the advantages of simple process, controllable conditions, good safety and eco-friendly. In this review, the recent progress in synthesizing different types of Cu-based catalysts by means of the electrochemical method are comprehensively reviewed. The engineering strategies and the effects of the key preparation conditions on the catalytic performance of CO 2 electroreduction for C 2+ products are discussed in details. Besides, copper-based catalysts synthesized by electrochemical methods combined with the ordinary methods (wet chemical methods, plasma activated methods and other methods) were also outlined. Finally, the development potential of electrochemical synthesis for Cu-based catalysts are recommended, which provides a direction for the future development of Cu-based catalysts with low cost and high ECR performance. [ABSTRACT FROM AUTHOR]

Abstract The oxygen reduction reaction (ORR) is one of the core reactions that occur in fuel cells and metal air batteries. Metal-free catalysts such as porous carbons are promising candidates for ORR and the performance of porous carbons strongly depends on their nanostructure. Herein, we reported the synthesis of high surface area N doped carbon nanotube (CNT-900) by using ZnO@zeolite imidazolate framework (ZnO@ZIF-8) nanowire as a precursor. When used for an ORR catalyst, the CNT-900 show obvious superior performance compared with the carbon derived from ZIF-8. In addition, it exhibits comparable activity with 20 wt% Pt/C and superior stability. Combined with green and facile synthesis strategy, the method in this work can be easily extended to synthesis other nanomaterials for energy storage and conversion application. Graphical abstract N doped carbon nanotube with high surface area and ORR performance was synthesized by using ZnO@ZIF-8 nanowire as precursor. Unlabelled Image Highlights • ZnO@ZIF-8 was facilely synthesized at room temperature and converted to N doped carbon nanotube at 900 °C. • The CNT-900 shows very high surface area, which greatly improves its ORR performance. • The CNT-900 exhibits comparable activity with 20 wt% Pt/C and superior stability. [ABSTRACT FROM AUTHOR]

1 3D homogeneous porous Cu-Ce catalyst was prepared by ordered SiO 2 microspheres as template. 2 3DHP catalyst exhibits superior photothermal catalytic performance for CO-PROX in H 2 -rich gas. 3 The uniform pore structure of 3DHP enhances the light absorption by photonic crystals effect. 4 Smaller particle size and higher S BET of 3DHP contribute to the highly dispersed Cu species. Photothermal preferential oxidation of CO (CO-PROX) on copper-ceria catalyst has emerged as an efficient and energy-saving approach for trace CO purification in hydrogen-rich gas. However, the limited light absorption and photo-to-thermal conversion capability of the copper-ceria catalyst hinder its catalytic performance for photothermal CO-PROX. In this study, a three-dimensional homogeneous porous copper-ceria catalyst (3DHP) was developed by using ordered SiO 2 microspheres as the hard template. Compared to 3DIP catalyst with disordered silica colloid as the template, the uniform 3D pore structure, smaller particle size and abundant oxygen vacancy in 3DHP remarkably promote its photothermal catalytic performance for CO-PROX driven by the simulated solar light. The uniform 3D pore structure of 3DHP catalyst greatly strengthens the light absorption and photo-to-thermal conversion ability due to the slow photon effect of photonic crystals, which obtained higher surface temperature under the light irradiation. The higher specific surface area contributed to the high dispersion of copper species on 3DHP catalyst. Additionally, the more abundant oxygen vacancy facilitated the activation of O 2 and the efficient electron-hole separation in 3DHP catalyst. Moreover, the visible light contributes to the largest portion of the total CO conversion due to the strong absorption ability of 3DHP in this range. [Display omitted] [ABSTRACT FROM AUTHOR]

Aiming for purification the trace amount of CO in H 2 -rich streams with reduced energy consumption and low cost, solar-driven photothermal preferential oxidation of carbon monoxide on the non-precious metal oxide catalyst is proposed in this work. Cu doped CuCeO 2−x nanorods catalysts were synthesized with a fast and simple coprecipitation method at the room temperature, which shows high CO oxidation activity in photothermal preferential oxidation of CO (CO-PROX) under UV-Vis-IR light irradiation. Rely on the various characterization methods such as UV-Vis-IR diffuse reflection spectrum (UV-Vis-IR DRS), photoluminescence spectrum (PL), transient photocurrent test, HRTEM, XRD, XPS, UV-Raman and H 2 -TPR, the optical and chemical properties of the CuCeO 2−x nanorods catalysts were uncovered. The photothermal catalytic activity of CuCeO 2−x nanorods doped with 10 wt% Cu reaches to 90% CO conversion under Xe lamp illumination (2.5 suns), and the solar driven photothermal CO-PROX reaction on CuCeO 2−x nanorods were proposed to be proceeded by the light-to-thermal conversion and subsequently to drive a thermal catalytic process. The catalytic performance of CuCeO 2−x nanorods in photothermal CO-PROX is closely related to the photo-to-thermal conversion efficiency and Cu-Ce synergetic interaction of CuCeO 2−x nanorods catalyst. The introduction of CuO x greatly broaden the optical absorption range and promotes the light absorption capacity of ceria nanorods, which induces the catalyst with high photo-to-thermal conversion capability. Moreover, the optimal copper dopant benefits to enhance the Cu-Ce synergetic interaction and accelerate the oxidation reaction taking place at low temperature. CuCeO 2−x nanorods catalyst shows promising competitive activity and ultra-low cost compared with the noble-based catalyst for the purification of hydrogen streams by the clean and eco-friendly sunlight sources. [Display omitted] • Solar-driven photothermal CO-PROX on non-precious CuCeO 2−x is achieved. • CuCeO 2−x nanorods were synthesized by fast coprecipitation at room temperature. • Optimal copper dopant promotes visible light absorption and redox property of ceria. • Photo-to-thermal conversion and Cu-Ce synergy interaction both affect the activity. [ABSTRACT FROM AUTHOR]

Pt/carbon fiber composite (Pt/Cf) with a low Pt loading of 1.0 wt% is introduced into dye-sensitized solar cells as counter electrode (CE) catalyst. The cobalt-electrolyte based device using this composite CE achieves power conversion efficiency of 8.97%, a great improvement of 40.4% as compared to the Cf CE based device. This research provides a feasible route to reduce the dosage of Pt in DSCs system, benefiting for the commercial application of DSCs. [ABSTRACT FROM AUTHOR]

• Theoretical calculation is an effective way to save endeavors for designing and choosing high performance catalysts for NRR. • Theoretically determine the effect of different doping methods, doping positions and quantities on material properties. • Provide theoretical basis and guidance for exploring new carbon catalysts. Ammonia (NH 3) is recognized as a chemical substance that is very important for the development of human society. At present, the traditional industrial synthetic ammonia process is Haber-Bosch, which has some shortcomings such as low conversion rate, high energy consumption and greenhouse gas emission. Therefore, the search for new synthetic ammonia methods has attracted the attention of many scientific researchers. In this work, we use density functional theory (DFT) to explore vacancy and heteroatom (N, S) doped defective carbon materials suitable for catalyzing nitrogen reduction reaction (NRR). The introduction of vacancy defect, N or S atom doping graphene can improve the reactivity of graphene. In addition, the high activity sites of defective graphene mainly distribute on the carbon atoms at the upper left edge, the right edge and the lower edge. The research results theoretically determine the effect of different doping methods, doping positions and quantities on material properties, and provide theoretical basis and guidance for exploring new carbon catalysts. [ABSTRACT FROM AUTHOR]

• MOR mechanism on PtNi catalyst is theoretically studied on four crystal planes doped with one-to-three Ni atoms. • The main path of CO poisoning on the catalyst surface: CH 3 OH → CH 2 OH → CHOH → CHO → CO was studied. • It is proved by calculation that the selected 1,2,3Ni-Pt (2 0 0) reduces the relative energy of the overall reaction path, possessing good catalytic effect on MOR with certain anti-CO toxicity. The anodic methanol oxidation reaction (MOR) generates a toxic intermediate CO in direct methanol fuel cell (DMFC), where the Pt catalyst is easily deactivated and the catalytic activity will be inevitably lowered. Alloying modification is an important approach to improve the anti-CO ability of Pt catalyst. In this work, MOR mechanism on PtNi catalyst is theoretically studied on four crystal planes doped with one-to-three Ni atoms. The main path of CO poisoning on the catalyst surface: CH 3 OH → CH 2 OH → CHOH → CHO → CO was studied. Meanwhile, the adsorption of PtNi catalyst on the reaction intermediate was carried out. Based on the relative energy Δ E , the four optimal catalysts were compared for MOR. Building on the above comprehensive evaluations the appropriate catalysts were finally selected by the activation effect. It is proved by calculation that the selected 1,2,3Ni-Pt (2 0 0) reduces the relative energy of the overall reaction path, possessing good catalytic effect on MOR with certain anti-CO toxicity. [ABSTRACT FROM AUTHOR]

• Mechanism of NRR occurred on Ru/graphene catalysts were studied by DFT. • The effects of Ru atom numbers and Ru atom distribution on Ru/Gr were studied. • Provide guidance for the design and preparation of NRR catalysts. As a more common catalyst material in nitrogen reduction reactions (NRR), Ru has high activity and considerable catalytic performance, but it is expensive with scarce reserves. These factors limit the development of Ru in NRR, how to reduce costs and increase the utilization of precious metals is a problem facing the development of Ru-based catalysts. Graphene is considered as a promising carrier material, which can increase the specific surface area and dispersibility of the catalyst, thereby improving the utilization rate of materials. Therefore we combined these two materials and studied the mechanism of NRR occurred on Ru/graphene (Gr) catalysts by density functional theory (DFT) method. The effects of different numbers of Ru atoms and Ru atom distribution on the catalytic activity of Ru/Gr catalyst were calculated. A series of data such as the adsorption free energy and reaction path were obtained. The final results show that the double Ru supported graphite nitrogen doped Gr with single adsorption process and the three Ru supported pyrrole nitrogen doped Gr with double adsorption process have the best NRR activity. Compared with catalyst-free process, the presence of the catalyst effectively reduces the reaction energy barrier and improves the reaction activity. The research results provide guidance for the design and preparation of high-performance NRR catalysts to a certain extent. [ABSTRACT FROM AUTHOR]