To investigate the hypothesis that molecules acting as crystallization inhibitors in solution could be transformed into crystallization promoters, additives were synthesized that mimic the pharmaceuticals acetaminophen and mefenamic acid and also possess polymerizable functionality. It was found that, in solution, these additives face-selectively inhibit crystal growth and lead to overall slower crystal appearance. In contrast, when the tailor-made additives were incorporated into an insoluble polymer, the induction time for the onset of crystal formation for both pharmaceuticals was substantially decreased. This approach now allows for the synthesis of tailor-made polymers that decrease the induction time for crystal appearance and may find application in compounds that are resistant to crystallization or in improving the fidelity of heteronucleation approaches to solid form discovery.

We report the tuning of CuFeO2 photoelectrodes by Mg doping and Cu deficiency to demonstrate the effects of carrier concentration on the photoresponse.

We report the carrier transport properties of CuIn­(S1–x Se x )2 (0 ≤ x ≤ 1), a promising chalcopyrite semiconductor series for solar water splitting. A low concentration Mg dopant is used to decrease the carrier resistivity through facilitating bulk p-type transport at ambient temperature. Temperature-dependent resistivity measurements reveal a four-order magnitude decrease in bulk electrical resistivity (from 103 to 10–1 Ohm cm) for 1% Mg-doped CuIn­(S1–x Se x )2 as x increases from 0 to 1. Hall effect measurements at room temperature reveal p-type majority carrier concentrations that vary from 1015 to 1018 cm–3 and mobilities of approximately 1–10 cm2 V–1 s–1. These results provide insights into the fundamental carrier transport properties of CuIn­(S1–x Se x )2 and will be of value in optimizing these materials further for photoelectrochemistry applications.

Cu(In,Ga)(S,Se) 2 (CIGS) chalcopyrites and their derivatives are potential candidates for use in photoelectrochemical (PEC) H 2 generation because of their well-matched solar absorption properties and agreeable band positions relative to the water reduction redox potential. In this work, we present the photoelectrochemical characterization and H 2 evolution performance of the highly tunable anion CIGS derivative series CuIn(S 1−x Se x ) 2 . The photocathodes were subjected to Mott−Schottky analysis and chopped-light irradiation to determine their flat band potential. With excellent agreement between the two techniques, the flat band potentials were determined to increase successively with increasing x in CuIn(S 1−x Se x ) 2 , with all band positions possessing appropriate energetics for the thermodynamic requirement of reducing H 2 O to H 2 . The photocathodes were then subjected to identical bulk H 2 evolution conditions for 10−12 h, maintaining ∼90% faradaic efficiency. The rates of photoelectrocatalysis were found to vary significantly within the CuIn(S 1−x Se x ) 2 series, ranging over 2 orders of magnitude using a constant light intensity of 100 mW/cm 2 . Carrier transport behavior beyond the space charge region where charge diffusion dominates is suggested as a limiting factor for the H 2 evolution rate of these p-type materials through the indirect influence of the majority carrier concentration.

Photoelectrochemical catalysts are often plagued by ineffective interfacial charge transfer or nonideal optical conversion properties. To overcome this challenge, strategically pairing a catalytically inactive, optically proficient semiconductor with a selective electrocatalyst, coined “catalytic mismatching”, is suggested. Here, chalcopyrite semiconductor CuInSe2 is paired with the electrocatalyst Ni3Al to selectively reduce CO2. This catalytically mismatched system produces methanol at a Faradaic efficiency 25 times greater than that achieved using the purely electrochemical Ni3Al system while reducing the operating potential requirement by 600 mV. These results suggest that catalytic mismatching is a promising tactic to achieve reaction selectivity in synergistic photoelectrochemical CO2 reduction systems.