Inspiration from nature for heterogeneous catalysis

The desire to attain high activity and selectivity achieved by systems in Nature has long been a source of inspiration for research in heterogeneous catalysis, and significant progress has been made. A summary is presented here of the progress in applying concepts in enzymes and cellular systems to develop artificial systems. The discussion is organized according to the length scale: dimensions of small molecules (∼1 nm), protein (nm-μm), and cells (∼ μm). At the smallest dimension, the focus is on the active site, and effects observed include functional group cooperation, substrate partitioning, site isolation, transition state stabilization, and pK shifts. At the intermediate dimension of a protein, effects observed include size exclusion, steric constraint, and docking and induced fit. Interestingly, the oscillation phenomenon observed in artificial systems, which is due to collective behavior of atoms, is not observed in natural systems. At the largest, cellular scale, processes of interest include cascade reaction and tandem reactions, and metabolon is one natural system to emulate. There are interesting but nascent developments to emulate phenomena such as self-healing, stimuli-responsiveness, reaction coupling, and designed hierarchical distribution of pores and channels across all scales. Much could be gained if catalysts can be designed to incorporate these properties.