Ultrasensitive electrode-free and co-catalyst-free detection of nanomoles per hour hydrogen evolution for the discovery of new photocatalysts

TL;DR

This paper introduces a highly sensitive, electrode-free method for detecting minimal hydrogen evolution rates, enabling rapid screening of new photocatalysts without co-catalysts or electrical bias.

Contribution

The study presents a novel detection system capable of measuring ultra-low hydrogen evolution rates in bare photocatalysts, facilitating the discovery of promising materials with minimal initial activity.

Findings

Detection of hydrogen evolution as low as 11.4 nmol/h/0.04g in bare TiO2.

Identification of ZnFe2O4 and Ca2PbO4 as promising photocatalysts without co-catalysts.

Comparable hydrogen evolution rates to literature for loaded TiO2.

Abstract

High throughput theoretical methods are increasingly used to identify promising photocatalytic materials for hydrogen generation from water as a clean source of energy. While most promising water splitting candidates require co-catalyst loading and electrical biasing, computational costs to predict them apriori becomes large. It is therefore important to identify bare, bias-free semiconductor photocatalysts with small initial hydrogen production rates, often in the range of tens of nano-mols per hour, as these can become highly efficient with further co-catalyst loading and biasing. Here we report a sensitive hydrogen detection system suitable for screening new photocatalysts. The hydrogen evolution rate of the prototypical rutile TiO2 loaded with 0.3 % wt Pt is detected to be 78.0+-0.8 {\mu}mol/h/0.04g, comparable with the rates reported in the literature. In contrast, sensitivity to an ultralow evolution rate of 11.4+-0.3 nmol/h/0.04g is demonstrated for bare polycrystalline TiO2 without electrical bias. Two candidate photocatalysts, ZnFe2O4 (18.1+-0.2 nmol/h/0.04g) and Ca2PbO4 (35.6+-0.5 nmol/h/0.04g), without electrical bias or co-catalyst loading, are demonstrated to be potentially superior to bare TiO2. This work expands the techniques available for sensitive detection of photocatalytic processes towards much faster screening of new candidate photocatalytic materials in their bare state