Solar energy is by far the largest exploitable resource of renewable energy. The amount of solar energy incident on the earth in one hour is enough to power our planet for one year. One of the best ways to harvest solar energy is to build artificial photosynthetic devices (APDs) that use sunlight to split water and combine the liberated hydrogen with CO2 to form energy-rich liquid hydrocarbons (solar fuels). Such liquid fuels are easy to transport and store, and, importantly, allow us to continue using existing infrastructure.
Building large-scale, efficient, low-capital APDs is a very challenging task. There are three major challenges: (1) to identify membranes for the passage of proton or hydroxide, (2) to identify photoabsorbers with band gaps matching the solar spectrum, and (3) to identity electrocatalysts for the two half-cell reactions, the CO2 reduction reaction (CO2RR) and the oxygen evolution reaction (OER). Among those challenges, the identification of efficient electrocatalysts composed by earth-abundant and inexpensive materials represents the greatest task.
The goal of our research group centers on the discovery and development of more efficient, stable, and inexpensive electrocatalysts for artificial photosynthesis using computational approaches, including quantum mechanics (Density Functional Theory) and molecular mechanics (ReaxFF).
PROJECT 1. Develop Electrocatalysts for Oxygen Evolution
The OER is at the heart of any artificial photosynthetic process, and is required as an anodic reaction. Currently, even the state-of-art electrocatalysts possess a large overpotential for OER (> 0.25 V) and most of them are composed by expensive materials, which becomes a big obstacle for large scale application. We are using quantum mechanical methods to develop and screen more efficient OER electrocatalysts composed by inexpensive materials.
PROJECT 2. Develop Electrocatalysts for CO2 Reduction
Most of electrocatalysts can only reduce CO2 to CO or formic acid. Metallic copper is the only material that can reduce CO2 to significant quantity of hydrocarbons (methane and ethylene are the major products). However, a very negative applied voltage (U > -1.0 V vs SHE) is required to drive the reaction, which makes the whole process inefficient. We are using computational approaches to develop electrocatalysts for CO2 reduction.
PROJECT 3. Develop Heterogeneous Catalysts for Alkane Selective Oxidation
Besides solar fuel reseach, we are also interested in heterogeneous catalysis. We are paricularly interested in the catalytic reactions that can selectively oxidize inexpenisve alkane into more valuable fine chemicals.