Photocatalytic modeling for maximizing utilization of real‐time changing sunlight and rationalizing evaluation

Abstract

Because of very high potential barrier for thermionic emission and trap‐assisted charge recombination, photocatalytic reaction rate that determined by semiconductor‐cocatalyst interfacial electron transfer severely deviates from linearity to the photocatalyst dosage or to the light intensity. This makes it challenging to maximize utilization of practical irradiation by referring the parameters evaluated from method used in conventional catalysis. We here develop a model and predict that photocatalytic reaction rate positively correlates to photocatalyst concentration under weak illumination while the correlation becomes negative under intense irradiation. The theoretical simulation that matches the experimental values can be used to guide maximizing photocatalytic photon utilization under various intensity of irradiation. The strong correlation can rationalize photocatalytic evaluation instead of obtaining a numerically high value by excessively lowering the denominators. To realize efficient utilization of real‐time changing sunlight, we propose a reactor configuration that can optimize the amount of photocatalyst participating into the reaction.

Three-Channel Electron Transfer for Estimating Time Constants Correlated with Photocatalytic Photon Utilization

“…Upon separation of the variables, eq 4 can be Because the right side of eq can be a constant for a given system, the light intensity shown in eq 4 can shift toward weak irradiation with an increase in the time constant (Figure S3). , …”

“…The photoinduced potential difference ( V ) that resulted from the accumulation of electrons can be , where σ can be approximately 0.5 under illumination . Upon substitution of eq into eq Equation 7 indicates that with an increase in the time constant (τ), the increase in the density of electrons in the semiconductor can provide a large driving force for SC interfacial electron transfer and r iet‑te can increase quadratically.…”

“…According to eqs 5–7, the time constant (τ) for electron transfer plays a central but complex role that seems to contradict each other. ,,,,, To clarify the matter, next, we will discuss the composition of the electronic process for the transfer of electrons from the semiconductor to the solution.…”

“…Because of catalytic inertia, the time constant (τ leak ) for the leakage of photogenerated electrons from the semiconductor to the solution can be evidently greater than that via a cocatalyst (τ SCS and τ SCS–SB ) (Figure and Figure S2). , Thus, the term 1/τ leak shown in eqs 9 and 10 can be omitted. The relation shown in eq without consideration of the side/back reaction can be simplified: The time constant (τ 2C ) can be obtained by monitoring the decay of the potential biased on the photocatalyst (cocatalyst-loaded semiconductor) in the dark, where the interference of the side/back reaction can be eliminated.…”

Self-Promoted H2 Formation: The Feasibility of Photoinduced CO Removal for Lossless Hydrogen Purification

“…Let us begin with H 2 -promoted H 2 formation. Initially, we wish to conduct the photocatalytic reaction in slurry suspension . However, the H 2 consumption is severe (Figure S4).…”