02164nas a2200229   4500000000100000000000100001008004100002653002700043653002100070653002100091653003100112653003100143100002400174700001800198700002200216700002100238245017600259856008400435300001400519490000600533520139500539       2017                            d10abifunctional catalysts10aelectrochemistry10ametal tungstates10aoxygen evolution reactions10aoxygen reduction reactions1 aGuruprakash Karkera1 aTanmay Sarkar1 aMridula Bharadwaj1 aAnnigere Prakash00aDesign and Development of Efficient Bifunctional Catalysts by Tuning the Electronic Properties of Cobalt–Manganese Tungstate for Oxygen Reduction and Evolution Reactions  uhttps://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cctc.201700540  a3681-36900 v93 aAbstract Solid-state electrochemistry is drawing considerable interest as the interconversion of O2 and water playing an important role in energy conversion and storage technologies. With the aim of developing an efficient bifunctional catalyst by tuning the electronic properties and local structure around the 3d metal in CoWO4, solid solutions of Co1−xMnxWO4 are investigated. Nanocrystalline Co1−xMnxWO4 (x=0 to 1) phases with a unique exposure of low surface energy planes are synthesized by hydrothermal methods. Replacing an optimum amount of Co with Mn to enhance the catalytic activity leads a observation of a negative shift in the Co2+/3+ redox wave and onset of the oxygen evolution reaction (OER), indicating a strong electronic interaction between the two elements. The composition corresponding to Co0.5Mn0.5WO4 has demonstrated great ability to catalyze both the OER and oxygen reduction reaction (ORR) with a combined overpotential of 0.89� V. It exhibited an OER current density of 10� mA cm−2 at an overpotential of 400� mV. Whereas ORR current density of 3� mA cm−2 is reached at a potential of 0.74� V versus reversible hydrogen electrode (RHE). The density functional theory revealed that the substitution of Mn in CoWO4 elevate the 3d metal d band center closer to the Fermi energy and hence ease the electron transfer to facilitate ORR and OER.