Journal Article carbon materials carbon spheres porous materials 7440-44-0 7631-86-9 Carbon Pd catalysts Polymers Research Support, U.S. Gov't, Non-P.H.S. Review Silicon Dioxide abundant oxygen vacancies alkynes’ semihydrogenation carbon catalysis carbon defects carbon surface chemistry chelated ion-exchange strategy colloidal spheres electrocatalysis hierarchical porous polymer hierarchical structures hypercrosslinked polymer intermetallics mesoporous material mesoporous materials mesoporous structure oxidative environment oxygen functional groups photocatalytic selective oxidation