No abstract

Zinc‐based electrochemistry is attracting significant attention for practical energy storage owing to its uniqueness in terms of low cost and high safety. However, the grid‐scale application is plagued by limited output voltage and inadequate energy density when compared with more conventional Li‐ion batteries. Herein, we propose a latent high‐voltage MnO2 electrolysis process in a conventional Zn‐ion battery, and report a new electrolytic Zn–MnO2 system, via enabled proton and electron dynamics, that maximizes the electrolysis process. Compared with other Zn‐based electrochemical devices, this new electrolytic Zn–MnO2 battery has a record‐high output voltage of 1.95 V and an imposing gravimetric capacity of about 570 mAh g−1, together with a record energy density of approximately 409 Wh kg−1 when both anode and cathode active materials are taken into consideration. The cost was conservatively estimated at

Product selectivity in multielectron electrocatalytic reactions is crucial to energy conversion efficiency and chemical production. However, a present practical drawback is the limited understanding of actual catalytic active sites. Here, using as a prototype single-atom catalysts (SACs) in acidic oxygen reduction reaction (ORR), we report the structure–property relationship of catalysts and show for the first time that molecular-level local structure, including first and second coordination spheres (CSs), rather than individual active atoms, synergistically determines the electrocatalytic response. ORR selectivity on Co-SACs can be tailored from a four-electron to a two-electron pathway by modifying first (N or/and O coordination) and second (C–O–C groups) CSs. Using combined theoretical predictions and experiments, including X-ray absorption fine structure analyses and in situ infrared spectroscopy, we confirm that the unique selectivity change originates from the structure-dependent shift of active sites from the center Co atom to the O-adjacent C atom. We show this optimizes the electronic structure and *OOH adsorption behavior on active sites to give the present “best” activity and selectivity of >95% for acidic H2O2 electrosynthesis.

Antisolvent addition has been widely studied in crystallization in the pharmaceutical industries by breaking the solvation balance of the original solution. Here we report as imilar antisolvent strategy to boost Zn reversibility via regulation of the electrolyte on amolecular level. By adding for example methanol into ZnSO 4 electrolyte,t he free water and coordinated water in Zn 2+ solvation sheath gradually interact with the antisolvent, whichm inimizes water activity and weakens Zn 2+ solvation. Concomitantly,d endrite-free Zn deposition occurs via change in the deposition orientation, as evidenced by in situ optical microscopy. Zn reversibility is significantly boosted in antisolvent electrolyte of 50 %m ethanol by volume (Anti-M-50 %) even under harsh environments of À20 8 8Ca nd 60 8 8C. Additionally,t he suppressed side reactions and dendrite-free Zn plating/stripping in Anti-M-50 %e lectrolyte significantly enhance performance of Zn/ polyaniline coin and pouchcells.Wedemonstrate this low-cost strategy can be readily generalized to other solvents,indicating its practical universality.R esults will be of immediate interest and benefit to ar ange of researchers in electrochemistry and energy storage.

Development of easy-to-make, highly active and stable bifunctional electrocatalysts for water splitting is important for future renewable energy systems. Three-dimensional (3D) porous Ni/Ni 8 P 3 and Ni/Ni 9 S 8 electrodes are prepared by sequential treatment of commercial Ni foam with acid activation, followed by phosphorization or sulfurization. The resultant materials can act as self-supported bifunctional electrocatalytic electrodes for direct water splitting with excellent activity towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. Stable performance can be maintained for at least 24 h, illustrating their versatile and practical nature for clean energy generation. Furthermore, an advanced water electrolyzer through exploiting Ni/Ni 8 P 3 as both anode and cathode is fabricated, which requires a cell voltage of 1.61 V to deliver a 10 mA cm -2 water splitting current density in 1.0 M KOH solution. This performance is significantly better than that of the noble metal benchmarkintegrated Ni/IrO 2 and Ni/Pt-C electrodes. Therefore, these bifunctional electrodes have significant potential for realistic large-scale production of hydrogen as a replacement clean fuel to polluting and limited fossil-fuels.

In this review, we focus on analysing the fundamental electronic, optical and chemical properties of 2D phosphorene to assess its suitability as a metal-free water splitting photocatalyst.

The establishment of electrocatalysts with bifunctionality for efficient oxygen evolution (OER)-and hydrogen evolution (HER)-reaction in acidic environments is a significant challenge to develop proton exchange membrane (PEM) water electrolyzers for production of clean hydrogen fuel. RuIr alloy was reckoned a promising electrocatalyst because of favorable OER performance and potential for HER. Here, we report the design of a bifunctional electrocatalyst with greatly boosted water splitting performance from doping RuIr alloy nanocrystals with transition metals that modify electronic structure and binding strength of reaction intermediates. Significantly, Co-RuIr resulted in small overpotentials of 235 mV for OER and 14 mV for HER (@ 10 mA cm -2 current density) in 0.1 M HClO 4 media. Therefore a cell voltage of just 1.52 V was needed for overall water splitting to produce hydrogen and oxygen. More importantly, for a series of M-RuIr (M = Co, Ni, Fe), the catalytic activity dependence at fundamental level on the chemical/valence states was used to establish a novel composition-activity relationship. This permits new design principles for bifunctional electrocatalysts.

Rhenium disulfide (ReS2) is a two dimensional (2D) group VII transition metal dichalcogenide (TMD). It is attributed with structural and vibrational anisotropy, layer independent electrical and optical properties, and metal-free magnetism properties. These properties are unusual compared with more widely used group VI-TMDs e.g. MoS2, MoSe2, WS2 and WSe2. Consequently, it has attracted significant interest in recent years and is now being used for a variety of applications including solid state electronics, catalysis, and, energy harvesting and energy storage. It is anticipated that ReS2 has the potential to be equally used in parallel with isotropic TMDs from group VI for all known applications and beyond.Therefore, a review on ReS2 is very timely. In this first review on ReS2, we critically analyze the available synthesis procedures and their pros-cons, atomic structure and lattice symmetry, crystal structure and growth mechanisms with an insight to the orientation and architecture of domain and grain boundaries, decoupling of structural and vibrational properties, anisotropic electrical, optical and magnetic properties impacted by crystal imperfections, doping and adatoms adsorptions, and the contemporary applications in different areas.