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Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu1.5Mn1.5O4, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORR vs RHE) to that of IrO2 and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO2 for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.

A two-step solution chemistry route was used to synthesize ternary Chevrel phase (Cu 2 Mo 6 S 8 ) with 5 h annealing at 1000 • C under reducing atmosphere. The approach marks a synthesis route different from hitherto described conventional solid-state methods. X-ray diffraction and scanning electron micrograph shows the formation of ∼1-1.5 μm size cuboidal shape Cu 2 Mo 6 S 8 crystals with unit cell dimensions a ∼ 0.96245 nm and c ∼ 1.01987 nm of molar volume ∼818.14 × 10 −3 nm 3 . De-cuprated Mo 6 S 8 exhibits a discharge capacity ∼76 mAhg −1 with good capacity retention up to ∼50 cycles when cycled at the current rate of 20 mA/g (∼C/6). The excellent rate capability and high Coulombic efficiency (∼99.3% at ∼1.5C rate) of the Mo 6 S 8 cathode renders the solution chemistry route an alternative approach for the synthesis of cuprated Chevrel phase: a known cathode system for magnesium battery.Electrochemical energy storage technologies based on rechargeable batteries are considered as one of the leading emerging technologies for stationary power application. Current battery technologies based on lead acid, nickel metal hydride, sodium-sulfur, and vanadium flow systems used for stationary power applications suffer due to various environmental and economic concerns. 1 Li-ion batteries used for mobile electronics and electric vehicles can offer high energy density, however, with lithium's geographically constraint reserve and high cost makes it imperative to explore alternative battery technologies. 2 Recently, energy storage systems based on bivalent Mg 2+ ions is being touted as a promising high energy density alternative battery system among others. 3,4 Magnesium (Mg) has several positive attributes which set it apart from the Li-ion battery system. 5 It is environmental friendly, cost effective (∼$ 2700/ton for Mg compared to $64,000/ton for Li) and is relatively more abundant in the earth's crust (∼13.9% Mg compared to ∼0.0007% of Li) compared to hitherto used popular systems. 6-8 Additionally, magnesium is more stable in air compared to lithium, and is theoretically capable of rendering higher volumetric capacity (3832 mAh/cm 3 for Mg vs. 2062 mAh/cm 3 for Li). Furthermore, magnesium is not plagued by dendrite formation unlike lithium metal batteries which led to initial safety concerns that was thankfully obviated by the intercalation of Li into graphite. 9,10 Earlier studies shows that conventional salts such as Mg(ClO 4 ) 2 , Mg(CF 3 SO 3 ) 2 , Mg[(CF 3 SO 2 ) 2 N] 2 etc. dissolved in various nonaqueous solvents develop surface passivation on the Mg anode and effectively block Mg 2+ ion transport. 11-13 On the other hand, Grignard's reagents (RMgX, R alkyl or aryl; X = Cl, Br) dissolved in ethereal solvents are well-known and are capable of electrochemically depositing and dissolving magnesium. 14 However, the limited electrochemical window (∼1.5 V) of Grignard's reagents imposes a major barrier for their use in practical cell assemblies. Aurbach et al. 15,16 first invented Mg organohaloaluminate salts (R 2 ...

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