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Silicon photodetectors and camera chips are ubiquitous in the visible region of the spectrum and the near‐infrared. However, their large bandgap prevents their use at longer, technologically very important, wavelengths. The band‐edge‐modified rare‐earth detectors in silicon demonstrated here, fabricated using standard silicon technology tools, offer a route to these wavelengths and room‐temperature operation. Ion implantation of the usual n‐ and p‐type dopants, arsenic and boron, into commercial silicon wafers is used to fabricate a standard silicon p–n junction. Further implants of the rare earths, either Ce or Yb, are made into the depletion region to enable the extended long‐wavelength response. Detectivities up to 1.47 × 108 cm Hz1/2 W−1 and 2.89 × 107 cm Hz1/2 W−1 at 1.3 and 1.55 μm have been obtained with these simple planar devices. If integrated as lateral detectors in a silicon photonics platform, responsivities as good as standard silicon photodetectors in the visible and near‐infrared will be achievable.

Dendritic MoO3/Ag with good crystallinity has been prepared through an operando method. In the hydrogen evolution reaction (HER), this catalyst, which was designed to utilize the best properties of each component material, showed a high catalytic activity. After the precursor was drop-cast onto a glassy carbon electrode, a reductive potential was applied to the coated electrode, and H-2 evolution occurred within the range of potentials. The overpotential required to evolve H-2 at the benchmark rate decreased progressively with subsequent voltammetric cycles, until a steady state was reached at which only 145 mV of overpotential was required to pass -10 mA cm(-2) of current density. During the electrocatalysis, the precursor was converted to catalyst through an operando method. This operando-synthesized MoO3/Ag catalyst has a low Tafel slope (43 mV dec(-1)), low overpotential (145mV), and excellent durability for HER. It has the potential to be a promising material for HER.