The development of high-throughput and scalable techniques for patterning inorganic structures is useful for the improved function and efficiency of photonic and energy conversion devices. Here we demonstrate a facile and rapid electrochemical method for patterning periodic metallic and nonmetallic submicron structures over large areas. Si substrates have been patterned with arrays of periodically spaced lines, rings, squares, and terraces of main-group and transition-metal oxides. In addition to planar substrates, three-dimensional surfaces and their vertical sidewalls have been patterned. The features are 20(+/- 1) nm high and 360(+/- 15) nm wide, and their period is finely tunable in situ from 500 nm to 7 mu m. These features exhibit <3% variation in period and are rapidly patterned in <2 min. We demonstrate the versatility of the technique by rapidly patterning an efficient water splitting catalyst, Co phosphate oxide (CoPi), and show that the integrated materials system performs water splitting with complete Faradaic efficiency. More generally, the ability to pattern submicron structures over large areas in a facile, reliable, and timely manner may be useful for the fabrication of devices for energy, meta-material, and sensing applications.