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Multifunctional catalysts that integrate high efficiency hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activity in a single material are attractive for unitized regenerative fuel cells and overall water splitting technologies. As the best-known HER and ORR electrocatalysts, Pt and its alloys have only moderate OER activity. Ruthenium and iridium oxides exhibit the highest OER activities but not as active as Pt for HER and ORR. Here, we proposed a general principle for achieving trifunctional electrocatalysis for three reactions in a single material. Using the newly-synthesized pyrazine-modified graphdiyne (PR-GDY) as an example, we demonstrated that the synergistic effect of the pyridinic nitrogen and anchored transition-metal (TM) single atoms renders highly-efficient HER/OER/ORR trifunctional electrocatalytic activity. For the Ni-doped PR-GDY, the overpotentials for HER, OER and ORR can be respectively as low as −0.05, 0.29 and 0.38 V, which are comparable or even superior to the best-known single-functional and bi-functional precious electrocatalysts. These computational results offer not only a promising trifunctional electrocatalyst but also a strategy for the design of multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

• We demonstrated the Fe-PTC monolayer can serve as a trifunctional electrocatalyst. • Fe-PTC has high electrocatalytic activity for HER with overpotential is −0.23 V. • The p-band center as descriptor is used to reveal the origins of catalytic activity. • Fe-PTC is a potential electrocatalyst for both OER and ORR with low overpotentials. Integrating high efficiency hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in multifunctional electrocatalysts is attractive for the unitized regenerative fuel cells and overall water splitting technologies. We demonstrated from first-principles calculations the recently- synthesized two-dimensional (2D) metal-organic frameworks (MOFs), namely transition metal 1,2,3,4,5,6,7,8,9,10,11,12- perthiolated coronene (TM-PTC) have multifunctional electrocatalytic activity for HER, OER and ORR. In particular, Fe-PTC monolayer can serve as a trifunctional electrocatalyst for overall water splitting and rechargeable metal-air battery with low overpotentials comparable to those of the well-developed unifunctional electrocatalysts. The origins of the trifunctional electrocatalytic activity were also discussed. This work is expected to open an avenue for the design of highly-efficient multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals materials have been widely adopted as photocatalysts for water splitting, but the energy conversion efficiency remains low. On the basis of first-principles calculations, we demonstrate that the 2D Janus group-III chalcogenide multilayers: InGaXY, M 2 XY and InGaX 2 (M = In/Ga; X, Y = S/Se/Te), are promising photocatalysts for highly-efficient overall water splitting. The intrinsic electric field enhances the spatial separations of photogenerated carriers and alters the band alignment, which is more pronounced compared with the Janus monolayers. High solar-to-hydrogen (STH) efficiency with the upper limit of 38.5% was predicted in the Janus multilayers. More excitingly, the Ga vacancy of InGaSSe bilayer effectively lowers the overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to the levels provided solely by the photogenerated carriers. Our theoretical results suggest that the 2D Janus group-III chalcogenide multilayers could be utilized as highly efficient photocatalysts for overall water splitting without the needs of sacrificial reagents. [ABSTRACT FROM AUTHOR]