Maoxiang Wu

Multisource Synergistic Electrocatalytic Oxidation Effect of Strongly Coupled PdM (M = Sn, Pb)/N-doped Graphene Nanocomposite on Small Organic Molecules

A series of palladium-based catalysts of metal alloying (Sn, Pb) and/or (N-doped) graphene support with regular enhanced electrocatalytic activity were investigated. The peak current density (118.05 mA cm−2) of PdSn/NG is higher than the sum current density (45.63 + 47.59 mA cm−2) of Pd/NG and PdSn/G. It reveals a synergistic electrocatalytic oxidation effect in PdSn/N-doped graphene Nanocomposite. Extend experiments show this multisource synergetic catalytic effect of metal alloying and N-doped graphene support in one catalyst on small organic molecule (methanol, ethanol and Ethylene glycol) oxidation is universal in PdM(M = Sn, Pb)/NG catalysts. Further, The high dispersion of small nanoparticles, the altered electron structure and Pd(0)/Pd(II) ratio of Pd in catalysts induced by strong coupled the metal alloying and N-doped graphene are responsible for the multisource synergistic catalytic effect in PdM(M = Sn, Pb) /NG catalysts. Finally, the catalytic durability and stability are also greatly improved.

Co-intercalation of multiple active units into graphene by pyrolysis of hydrogen-bonded precursors for zinc–air batteries and water splitting

Multifunctional electrocatalyst enabled electrochemical hydrogen/oxygen redox plays pivotal roles in variable energy conversion/storage devices and some coupling devices. The daunting challenge in developing multifunctional electrocatalysts at present is to effectively incorporate multiple active sites into one material. Herein, we presented a general protocol by a controllable pyrolysis/vapor reforming process, which allows for reconstitution to form CoNC nano-units, while preserving Co and Co oxides simultaneously. The material by co-intercalation of these active units into graphene generates outstanding trifunctional activities. The overpotentials for hydrogen and oxygen evolution reactions are 205 and 360 mV (at 10 mA cm−2), respectively, and the half-wave potential for the oxygen reduction reaction is 0.81 V, outperforming most of the state-of-the-art trifunctional electrocatalysts. A maximum power density of 23 mW cm−2 and 1000 stable cycles were realized in the as-prepared material equipped Zn–air battery. This battery further drove overall water splitting for 24 hours, at a faradaic efficiency of ca. 100% and gas production rate of 0.035 and 0.017 mL min−1 for hydrogen and oxygen, respectively. Thus this work offers a general approach to explore other efficient multifunctional electrocatalysts for application in renewable energy technologies.

A porous Zn cathode for Li–CO2 batteries generating fuel-gas CO

Global climate change and energy concerns trigger worldwide interest in sustainable, economical CO2 reductive transformation into valuable chemicals. However, traditional electro/thermo-catalysis strategies usually consume a large amount of energy and suffer from low efficiency. Herein, a three-dimensional porous fractal Zn cathode is synthesized by redox-coupled electrodeposition and it exhibits excellent electrocatalytic properties for CO2-to-CO conversion. Inspired by the coupling of a metal battery and CO2 electroreduction, a novel fuel-gas CO generating Li–CO2 battery is firstly realized with the as-prepared porous fractal Zn cathode. Meanwhile, CO formation can be easily tuned within a wide range of discharge currents and reach a maximum faradaic efficiency of up to 67%. Finally, based on gas and solid discharge product analysis, the related mechanism of CO main product production is proposed as 2Li+ + 2CO2 + 2e− → CO + Li2CO3. Hence the present work presents a new way for the further development of metal–CO2 batteries to generate useful chemicals and fuels besides electrical energy.

Synergistic Supports Beyond Carbon Black for Polymer Electrolyte Fuel Cell Anodes

Polymer electrolyte fuel cells (PEFCs) are among the most advanced energy technologies with low operating temperatures, high energy densities, ease of transportation and storage. However, the deficiencies such as low activity and high cost of the electrocatalysts at anodes greatly hinder their commercialization. The commonly used carbon black supports lack the capacity of regulation over the supported noble metals towards efficient electro‐catalytic oxidation of fuels. In this Mini‐Review, the prerequisite factors in advanced supports are outlined, ranging from self‐supported precious metal alloys as well as non‐noble metal materials, while simultaneously revealing the superiorities of some advanced supports beyond carbon black in terms of electronic conductivity, synergy with surface precious metals, chemical and electrochemical stability, and other possible interactions. The effects arisen from microscopic morphology, nano‐structure, and composition on the electrocatalytic activity/stability are also discussed. Finally, several of the most promising supports are highlighted, and the research trends of synergistic supports in future PEFCs are predicted.

CO2 Overall Splitting by a Bifunctional Metal‐Free Electrocatalyst

Photo/electrochemical CO2 splitting is impeded by the low cost-effective catalysts for key reactions: CO2 reduction (CDRR) and water oxidation. A porous silicon and nitrogen co-doped carbon (SiNC) nanomaterial by a facile pyrolyzation was developed as a metal-free bifunctional electrocatalyst. CO2 -to-CO and oxygen evolution (OER) partial current density under neutral conditions were enhanced by two orders of magnitude in the Tafel regime on SiNC relative to single-doped comparisons beyond their specific area gap. The photovoltaic-driven CO2 splitting device with SiNC electrodes imitating photosynthesis yielded an overall solar-to-chemical efficiency of advanced 12.5 % (by multiplying energy efficiency of CO2 splitting cell and photovoltaic device) at only 650 mV overpotential. Mechanism studies suggested the elastic electron structure of -Si(O)-C-N- unit in SiNC as the highly active site for CDRR and OER simultaneously by lowering the free energy of CDRR and OER intermediates adsorption.