Humanity is faced with the daunting task of meeting our ever-growing demand for resources without causing catastrophic climate change. If we are to eventually establish a sustainable society, we must learn to synthesize useful chemicals, fuels, and materials from readily abundant small molecules using renewable forms of energy. Taking inspiration from ecology, my group is developing nanoscale catalysts capable of converting common pollutants into useful chemicals using only photons or electrons as the energy input. In one approach, we exploit the unique light-matter interactions of plasmonic-metal nanoparticles for photochemical materials growth and evaluate how intrinsic material properties govern the quantum efficiency of plasmonic photocatalysis. In a separate strategy, we are developing the design rules for surfactant-free, electrochemical growth of shape-controlled metal nanoparticles for electrosynthesis of fuels and chemicals. We are particularly interested in understanding the reaction mechanism of electrochemical nitrate reduction into ammonia to produce fertilizer at ambient temperature and pressure. I will share my group’s latest efforts at elucidating the rate-determining step of this reaction and discuss the role of Cu surface structure in the reaction rate and selectivity for ammonia.