Clean hydrogen production via water electrolysis is incumbent upon the development of highperforming hydrogen evolution reaction electrocatalysts. Despite decades of commercial maturity, however, alkaline water electrolyzers continue to suffer from limitations in electrocatalytic activity and stability, even with noble metal catalysts. In recent years, combining platinum with oxophilic materials, such as metal hydroxides, has shown great promise for improving performance potentially by enabling stronger water dissociation at the surface of electrocatalysts. In this work, we leveraged the nanoscopic proportions and surface programmability of the filamentous M13 bacteriophage in the design, synthesis, and exceptional performance of 3D nanostructured biotemplated electrocatalysts for alkaline hydrogen evolution. We developed a facile synthesis method for phage-templated, Pt-Ni(OH)2 nanonetworks, relying on scalable techniques like electroless deposition and air oxidation. After optimization of the platinum content, our materials display-4.9 A mg-1 Pt at-70 mV versus the reversible hydrogen electrode, the highest reported mass activity in 1 M KOH to date, and undergo minimal changes in overpotential under galvanostatic operation at-10 mA cm-2 geo. Looking forward, the performance of these catalysts suggests that biotemplating nanostructures with M13 bacteriophage offers an interesting new route for developing high-performing electrocatalysts.

Here, we rationally assemble 1D biological templates into scalable, 3D structures to fabricate metal nanofoams with a variety of genetically programmable architectures and material chemistries.

Transition metal phosphides are a new class of materials generating interest as alternative negative electrodes in lithium‐ion batteries. However, metal phosphide syntheses remain underdeveloped in terms of simultaneous control over phase composition and 3D nanostructure. Herein, M13 bacteriophage is employed as a biological scaffold to develop 3D nickel phosphide nanofoams with control over a range of phase compositions and structural elements. Virus‐templated Ni5P4 nanofoams are then integrated as thin‐film negative electrodes in lithium‐ion microbatteries, demonstrating a discharge capacity of 677 mAh g–1 (677 mAh cm–3) and an 80% capacity retention over more than 100 cycles. This strong electrochemical performance is attributed to the virus‐templated, nanostructured morphology, which remains electronically conductive throughout cycling, thereby sidestepping the need for conductive additives. When accounting for the mass of additional binder materials, virus‐templated Ni5P4 nanofoams demonstrate the highest practical capacity reported thus far for Ni5P4 electrodes. Looking forward, this synthesis method is generalizable and can enable precise control over the 3D nanostructure and phase composition in other metal phosphides, such as cobalt and copper.