Controlled Periodic Illumination Enhances Hydrogen Production by over 50% on Pt/TiO2

Clarifying mechanisms and kinetics of programmable catalysis

Programmable catalysis-the purposeful oscillation of catalytic potential energy surfaces (PES)-has emerged as a promising method for the acceleration of catalyzed reaction rates. However, theoretical study of programmable catalysis has been limited by onerous computational demands of integrating the stiff differential equations that describe periodic cycling between PESs. This work details methods that reduce the computational cost of finding the limit cycle by ≳108×. These methods produce closed-form analytical solutions for didactic case studies, examination of which provides physical insights of programmable catalysis mechanisms. Generalization of these analyses to more complex reaction networks, including CO oxidation on Pt (111) surfaces, exposes the key catalyst properties required to achieve enhanced rates and conversions via one of two programmable catalysis mechanisms: quasi-static (high frequency) and stepwise (intermediate frequency). Analytical description of each mechanism is critical in understanding the consequences of the Sabatier principle on achievable rate enhancement through programmed catalysis.

Artificial Molecular Ratchets: Tools Enabling Endergonic Processes

Non-equilibrium chemical systems underpin multiple domains of contemporary interest, including supramolecular chemistry, molecular machines, systems chemistry, prebiotic chemistry, and energy transduction. Experimental chemists are now pioneering the realization of artificial systems that can harvest energy away from equilibrium. In this tutorial Review, we provide an overview of artificial molecular ratchets: the chemical mechanisms enabling energy absorption from the environment. By focusing on the mechanism type-rather than the application domain or energy source-we offer a unifying picture of seemingly disparate phenomena, which we hope will foster progress in this fascinating domain of science.

Heterojunction Design between WSe2 Nanosheets and TiO2 for Efficient Photocatalytic Hydrogen Generation

Design and fabrication of efficient and stable photocatalysts are critically required for practical applications of solar water splitting. Herein, a series of WSe2/TiO2 nanocomposites were constructed through a facile mechanical grinding method, and all of the nanocomposites exhibited boosted photocatalytic hydrogen evolution. It was discovered that the enhanced photocatalytic performance was attributed to the efficient electron transfer from TiO2 to WSe2 and the abundant active sites provided by WSe2 nanosheets. Moreover, the intimate heterojunction between WSe2 nanosheets and TiO2 favors the interfacial charge separation. As a result, a highest hydrogen evolution rate of 2.28 mmol/g·h, 114 times higher than pristine TiO2, was obtained when the weight ratio of WSe2/(WSe2 + TiO2) was adjusted to be 20%. The designed WSe2/TiO2 heterojunctions can be regarded as a promising photocatalysts for high-throughput hydrogen production.

Thermo-photo catalysis: a whole greater than the sum of its parts

Thermo-photo catalysis, which is the catalysis with the participation of both thermal and photo energies, not only reduces the large energy consumption of thermal catalysis but also addresses the low efficiency of photocatalysis. As a whole greater than the sum of its parts, thermo-photo catalysis has been proven as an effective and promising technology to drive chemical reactions. In this review, we first clarify the definition (beyond photo-thermal catalysis and plasmonic catalysis), classification, and principles of thermo-photo catalysis and then reveal its superiority over individual thermal catalysis and photocatalysis. After elucidating the design principles and strategies toward highly efficient thermo-photo catalytic systems, an ample discussion on the synergetic effects of thermal and photo energies is provided from two perspectives, namely, the promotion of photocatalysis by thermal energy and the promotion of thermal catalysis by photo energy. Subsequently, state-of-the-art techniques applied to explore thermo-photo catalytic mechanisms are reviewed, followed by a summary on the broad applications of thermo-photo catalysis and its energy management toward industrialization. In the end, current challenges and potential research directions related to thermo-photo catalysis are outlined.

Quantum yield enhancement in the photocatalytic HCOOH decomposition to H2 under periodic illumination

Despite numerous studies on controlled periodic illumination to improve the quantum yield of photocatalytic reactions, debates still exist on the nature of such effect. In our system, we proposed that enhanced electron transfer is the promotion mechanism.