The need for renewable energy has sparked widespread interest in photocatalysts, including systems based on plasmonic metal nanoparticles. To take advantage of these materials, a fundamental understanding of how plasmon-induced hot-carriers drive chemical reactions is needed. This work examines how different hot carrier distributions affect electrochemical reactions of plasmonic nanoparticles, and how applied electrochemical potentials can be used to modify the reactivity of hot carriers. Using hot-hole assisted gold nanorod electro-dissolution as a model system, I demonstrated that oxidation reactions are most efficiently driven by athermal holes in the d-band, rather than less energetic holes in the sp-band. Nanorods exhibited reactive hot-spots for d-band holes at the tips. To expand plasmon driven chemical reactions to other materials that allow more tunability of optical and electronic properties, the stability and degreadation mechanism of gold-silver alloy nanoparticles was explored. Alloying provided a significant improvement in nanoparticle stability. A two stage model for alloy nanoparticle degreadation was developed and confirmed using numerial simulations. Finally, with the vision dirving homogeneous reactions with plasmons, a mechanism for plasmon-induced generation of solvated electrons was demonstrated. Hot electrons were found to eject from nanoparticles into water, where they formed solvated electrons, which are powerful solution phase reducing agents. This fundamental insight reveals the opportunity for new reaction pathways for plasmon-induced reactions by moving the reaction site away from the particle surface.