Energetic hot electrons generated in Mn-doped quantum dots (QDs) via exciton-to-hot-electron upconversion possess long-range transfer capability. The long-range hot electron transfer allowed for superior efficiency in various photocatalytic reduction reactions compared to conventional QDs, which solely rely on the transfer of band edge electrons. Here we show that the synergistic action of the interfacial hole transfer to the initial reactant and subsequent long-range hot electron transfer to an intermediate species enables highly efficient redox-neutral photocatalytic reactions, thereby extending the benefits of Mn-doped QDs beyond reduction reactions. The photocatalytic conversion of formate (HCOO–) to carbon monoxide (CO), which is an important route to obtain a key component of syngas from an abundant source, is an exemplary redox-neutral reaction that exhibits a drastic enhancement of catalytic efficiency by Mn-doped QDs. Mn-doped QDs increased the formate to CO conversion rate by 2 orders of magnitude compared to conventional QDs with high selectivity. Spectroscopic study of charge transfer processes and the computational study of reaction intermediates revealed the critical role of long-range hot electron transfer to an intermediate species lacking binding affinity to the QD surface for efficient CO production. Specifically, we find that the formate radical (HCOO)•, formed after the initial hole transfer from the QD to HCOO–, undergoes isomerization to the (HOCO)• radical that subsequently is reduced to yield CO and OH–. Long-range hot electron transfer is particularly effective for reducing the nonbinding (HOCO)• radical, resulting in the large enhancement of CO production by overcoming the limitation of interfacial electron transfer.

Electrochemical erasing of conductive coatings at microscale for the fabrication of functional devices on flexible and hard surfaces is demonstrated. The nanoporous pyramidal-shaped nano-and micro-scale polyacrylamide hydrogel PLE probes allowed delivery of electrochemical etchants to the surface providing on-demand maskless patterning at microscale. Highly efficient erasing (silver and copper metals erasing efficiency ≈100%), areal erasing rate ≈80 m 2 /s, and pressure dependent spatial erasing feature dimensions between 3 m to many tens of microns on metal surfaces allowed fabrication of microelectrodes of various geometries. Overall, PLEbased microscale erasing allowed rapid and accessible fabrication of organic

There is a growing interest in the application of photogenerated hot electrons in semiconductor or metallic nanostructures such as in photocatalysis and photovoltaics taking advantage of their large excess kinetic energy and long-range transfer capability. Among various nanostructures that can generate hot electrons, Mn-doped semiconductors quantum dots (QDs) have shown their unique ability to produce highly energetic hot electrons via upconversion process. Compared to the plasmonic hot electrons, upconverted hot electrons in Mn-doped QDs possess several eV larger energy and can even produce photoelectron emission above the vacuum level from a subpopulation of hot electrons under weak visible excitation equivalent to the concentrated solar radiation. The present account reviews recent progresses made in the research on hot electron generation via upconversion and their application in photocatalytic reactions that highlights the benefits of long-range transfer of energetic hot electrons. K E Y W O R D S hot electron, photocatalysis, quantum dot, H 2 evolution, CO 2 reduction Chih-Wei Wang and Connor Orrison contributed equally to this study.