Innovative experimental techniques will also play a vital role in improving catalysis. Ultra-fast lasers, which emit bursts of light quicker than atoms move, now allow real-time tracking of catalytic processes in action. By using laser and other spectroscopic methods to identify the elusive transition states between reactants, products and catalysts, scientists aim to improve catalyst design and efficiency significantly. Automation also has the potential to revolutionize catalyst discovery: using high-throughput combinatorial synthesis, robotic instruments can screen the activity of large collections of different catalysts and hence speed up the identification of promising catalysts.
Biology continues both to inspire and to challenge catalysis researchers. For example, many processes in nature are regulated by interconnected catalytic networks that carefully switch chemical pathways on or off3. Organizing catalysts into such controlled systems, however, remains difficult. Another way in which researchers emulate nature is through directed evolution of biocatalysts in test tubes (Fig. 1)4. By subjecting enzyme-coding DNA sequences to iterative rounds of mutagenesis, screening and selection, it is possible to generate biocatalysts that are able to perform specific chemical duties such as selective oxidation of hydrocarbon chains.
The emerging field of organocatalysis seeks to improve upon natural catalytic systems by replacing, for example, entire protein chains with small organic molecules that mimic the active sites and hydrogen-bonding properties of larger biological entities5. Whether such molecules can be endowed with other desirable attributes of biocatalysts, such as molecular switching or allosteric control, remains to be seen.
Because good catalysts must survive many process cycles, intrinsically stable noble metals, such as ruthenium and gold, play important roles in both homogenous and heterogeneous catalysis6. Nature, by contrast, has developed extraordinarily selective catalysts that are free of noble metals. Can researchers find cheap, robust and industrially viable alternatives that can take over the role of increasingly scarce noble metals7?
A primary objective of heterogeneous-catalysis research is unravelling the secrets behind the adsorption, activation and desorption processes occurring on metal and metal oxide surfaces. Scanning tunnelling microscopy represents one way in which to achieve this goal; for example, recent studies revealed that platinum covered with a thin iron oxide film acts as a better catalytic converter than clean platinum (Fig. 2)8,9. Such unexpected results demonstrate that improved analytical tools can produce more rational catalyst designs.