7337wileyonlinelibrary.com energy and the development of regenerative fuel cells and rechargeable metal-air batteries. [1][2][3][4] Note that overpotentials originating from the polarization phenomenon occurring at the electrodes induce a larger voltage window than the theoretical minimum one (1.23 V) to afford thermodynamic driving force. [ 5,6 ] As such, the sluggish apparent reaction kinetics necessitates the utilization of noble-metal-based electrocatalysts to achieve respectable performance, i.e., Pt for HER and IrO 2 / RuO 2 for OER, [ 7,8 ] though the scarcity and the consequent unfavorable cost prohibit the scale-up deployment in energy devices. Accordingly, great efforts have been made toward effi cient earth-enriched materials, such as OER catalysts working under strongly alkaline conditions and HER catalysts operating in strongly acidic mediums, due to the thermodynamic convenience and application prospect in alkaline electrolyzers or proton-exchange membrane. [9][10][11][12][13][14][15] On the one hand, pairing the OER and HER catalysts together in the same electrolyte is of practical values to accomplish overall water splitting, which remains diffi cult to achieve owing to the incompatibility of the stability and activity for the same catalyst systems in the operating pH regions, thereby leading to inferior effi ciency; on the other hand, the different catalysts intended to separate HER and OER may need distinct synthetic strategies and instruments with lowthroughput preparation processes. [16][17][18][19][20] Therefore, it is still a grand challenge to exploit bifunctional electrocatalysts in terms of not only featuring high effi ciency toward both hydrogen and oxygen evolution reactions, but also simplifying the system and reducing the costs.Transition Co-based catalysts have been regarded as promising alternatives to noble metals to drive the half reactions, for instance, metal Co, [ 21 ] CoS, [ 22 ] and CoSe, [ 23 ] for HER and Co oxides/(oxy)hydroxides designed for OER. [ 24,25 ] Indeed, CoO xcarbon composites have been implemented to be bifunctional and effective electrocatalysts for overall water splitting in base, wherein the involvement of conductive carbonaceous hosts is to overcome the disadvantages of self-accumulation and insuffi cient electric conductivity as to oxides. [ 26,27 ] Nonetheless, the sophisticated preparation and instability of active phases in acid propose an obstacle to further optimize the technology and fi nd Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the innovative exploration regarding the design of effi cient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well-defi ned mesoporosity and a high specifi c surface area (148 m 2 g −1 ) can be directly employed as a bifunctional and fl exible working elect...

Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

Anode-free metal batteries can in principle offer higher energy density, but this requires them to have extraordinary Coulombic efficiency (>99.7%). Although Zn-based metal batteries are promising for stationary storage, the parasitic side reactions make anode-free batteries difficult to achieve in practice. In this work, a salting-in-effect-induced hybrid electrolyte is proposed as an effective strategy that enables both a highly reversible Zn anode and good stability and compatibility toward various cathodes. The as-prepared electrolyte can also work well under a wide temperature range (i.e., from −20 to 50 °C). It is demonstrated that in the presence of propylene carbonate, triflate anions are involved in the Zn2+ solvation sheath structure, even at a low salt concentration (2.14 M). The unique solvation structure results in the reduction of anions, thus forming a hydrophobic solid electrolyte interphase. The waterproof interphase along with the decreased water activity in the hybrid electrolyte effectively prevents side reactions, thus ensuring a stable Zn anode with an unprecedented Coulombic efficiency (99.93% over 500 cycles at 1 mA cm–2). More importantly, we design an anode-free Zn metal battery that exhibits excellent cycling stability (80% capacity retention after 275 cycles at 0.5 mA cm–2). This work provides a universal strategy to design co-solvent electrolytes for anode-free Zn metal batteries.