The demand of low cost materials has become one of the major challenges scientists face to address critical contemporary issues such as sustainable energy sources. For instance, one of the promising alternatives for the transition of fossil fuel-based energy to a clean and renewable technology relies on the widespread implementation of solar-related energy systems, however, the high cost of energy production poses an intrinsic limitation. In this context, low cost materials development is required to balance the necessary increase in power generation and conversion efficiency and the costs of implementation and operation. Furthermore, a better comprehensive understanding of materials growth and properties relationships using quantum confinement and nanoscale strategies to raise the theoretical limits by changing the fundamental physics and chemistry is the key to success. Such ideas were demonstrated by the thermodynamic modeling and low-cost design of crystalline arrays of quantum rods- and dots-based oxides with controlled orientation, size, and shape onto various substrates at nano-, meso-, and micro-scale by aqueous chemical growth at low-temperature. Tailored dimensionality effects on their surface chemistry, electronic structure, and energetics for a low cost and sustainable generation of hydrogen from the two most abundant and geographically-balanced free resources available on this planet, that is the sun and seawater were also presented.